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CESR Operator Training Info



The Machine

Gun → Linac → Snouts → Synchrotron → Transfer Lines → CESR → CHESS lines

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Overview

One of the initial challenges of getting started at CLASSE (Cornell Lab for Accelerator-Based Sciences and Education), also known as LEPP (Laboratory of Elementary Particle Physics), which is the umbrella that also holds Newman Lab and the Physical Sciences Building, is getting used to the jargon. This short overview is meant to be a quick introduction to the terms and names casually thrown around the lab, as well as basic laboratory concepts.

This laboratory houses a particle accelerator, i.e. a machine that takes particles – in our case, electrons and positrons (the antimatter counterpart of electrons, also known as anti-electrons) and accelerates them to high energy. Because the accelerator is roughly circular, it is often referred to as “the ring.”

The particle accelerator housed at CLASSE is actually comprised of three separate accelerators, which are connected by transfer lines. This is the first fundamental thing to understand about the accelerator structure: there is a linear component called the LINAC (linear accelerator), a ring called the synchrotron, and a second ring called CESR (Cornell Electron Storage Ring). It is pronounced “see-zer,” as in Julius. Because CESR is the raison d’etre of the laboratory, a lot of things get their name from it. For example, you are the CESR Operator. (There are many other activities in CLASSE besides CESR, e.g. ERL/ CBeta, cosmology, theory, dark photon experiment, bright beams, CMS, etc.)

Gun

The gun creates the initial electron beam that is propagated through the rest of the machine. It consists of a filament that is used to heat up a cathode. When the cathode reaches a certain temperature, it starts emitting electrons. The power supply of the gun provides a voltage of up to 160kV. Usual running conditions are 150kV.

We limit the timing and duration of electrons leaving the cathode with a grid. When the cathode is pulsed negatively, electrons are allowed to pass through the grid and are attracted to the anode by the 150kV. The cathode is pulsed for 3ns, which causes a bunch that is quickly focused to fit through a hole in the anode. After exiting the anode, the bunch enters the prebunchers at about 1 meter in length, at 150kV.

This is a drawing of our electron gun.

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More details about the gun are available in the Lin and Syn overview by Mike Billing.

Prebunchers and Injectors

Once the beam leaves the gun, it enters the Injector and Linac Section 1. As part of the injector system, located right after the gun, there are two prebuncher cavities. They are an essential part of increasing the acceleration of the electron beam, while also “bunching” it – shortening the length of the beam from 1m to 3mm.

This is also the first RF (radio frequency) system that we encounter in the ring. When a beam enters an RF cavity, the RF gives varying amounts of energy based on timing, with the end goal of having a denser bunch. This is done by having a 214 MHz RF wave inside the cavity, which provides or takes away energy to a particle depending on where in the wave cycle it enters the cavity.

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If a particle arrives late in the cycle, energy is pulled from it and it is “slowed down” (A), if it arrives early, it gains energy and gets “sped up” (B). The result is all of the particles get bunched into traveling at the same speed and time.

A second type of bunch control occurs in tandem with the prebunchers: the whole section is encompassed by a large solenoid. The solenoid focuses the beam by spiraling any particles that are outside of the main bunch in the transverse plane back into the bunch.

Linac

After exiting the injector, the electron beam enters the Linac, which is made up of 8 sections. The first four sections are designed to accelerate the beam to relativistic velocities. By section 4, the beam has reached 150 MeV.

If the machine is set to what we call “electron conditions”, then the electron beam will travel through all 8 sections of the Linac, reaching 350MeV, before being steered into the Synchrotron.

If the machine is set to what we call “positron conditions”, then the electron beam will travel until it reaches section 5 (also called the converter), where a tungsten target has been inserted in the path of the beam.

The target is attached to a movable arm, so in electron conditions it is remotely moved out of the beam path, allowing the electron beam to travel through section 5 without losses due to collisions. When electrons collide with the target, the result is a cloud of electrons, positrons, and many other radioactive elements (this is why the converter cave is the most radioactive area of the lab, since the resulting elements have a long half-life). If the electrons and positrons interact, they will annihilate each other. To avoid this, there are solenoids set up right past the converter. Their purpose is to turn the resulting positron cloud into a beam going in a straight line. Then, because the relativistic electron beam has turned into a positron cloud, sections 6-8 of the Linac must focus and re-accelerate the beam. Because the positrons only travel half of the distance of the Linac, they only reach 200MeV before entering the Snout.

Snouts

The snouts are transfer lines to the synchrotron, and allow each species to be injected in the proper direction.

The analyzer magnets only allow particles with the correct energy to enter the snouts, making outliers run into the walls of the snout because they aren’t bending at the correct angle.

The electron beam is bent 20 degrees counterclockwise in the snout, while the positron beam is bent 165 degrees clockwise.

The beam is injected into the synchrotron at an angle, to match the orbit (the orbit is the specific path the beam takes within the ring. The beampipe is fairly large, while the beam itself is fairly small, so the beam orbit is not limited to one specific path in perpetuity). Steering magnets are used to bend the entering beam to the correct angle, while the inflector is used to deflect the beam into the correct orbit.

Synchrotron

The Linac accelerates the beam to an acceptable energy range for it to enter the synchrotron. Once it’s inside the synchrotron, the beam can circle around and reach much higher energies than can be achieved with a Linac (unless the Linac was very long). The synchrotron thus bridges the gap in energy between the Linac (which operates at comparatively low energies) and the storage ring (which operates at high energy). In a synchrotron, the bunches are accelerated many times by 3 RF cavities, while the magnets change to bend the beam correctly with a control system that reacts before the beam interacts with the magnet. The guide field for the synchrotron is a DC-biased AC wave at 60Hz. We also don’t start at zero energy, as mentioned. Bunches are injected at low energy; the bottom of our sine wave. 3000 turns brings the energy up to the top of the sine wave, where it’s ready to be injected into CESR. Timing needs to be precise, so that the synch and CESR are synchronous. The peaking strip is used to reach this synchronicity.

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Transfer Lines

Once the beam in the synchrotron has reached the necessary energy, it is transferred into CESR. There are two transfer lines; one for positrons (in the west) and one for electrons (in the east).

Transferring the beam from the Synchrotron to CESR is an involved process: first, the beam in CESR itself must adjust its trajectory. To do this we have “pulsed magnets” (called this because of their instantaneous, pulse-like behavior – they are only turned on for an instant to alter the beam’s movement) called bumps: they are set up at three locations in both the west and the east, so each set is turned on when injecting the corresponding species. The bumps move the beam so that it is closer to the edge of the beampipe, and in the correct location to accept the incoming beam from the synchrotron. [the pulsed “bumps” actually are kicks that are coordinated and act as a single bump. This coordination is called closing the bump]

While the bumps are moving the stored beam, the kicker, located in the synchrotron, kicks the synch beam into the first DC septum, which gives the beam a kick that steers it into the second DC septum, which steer the beam into the third septum. The third septum, which is pulsed, kicks the beam the rest of the way into CESR.

CESR

The acronym stands for Cornell Electron Storage Ring. We are currently only storing positrons, so the name is not wholly accurate. The goal of the operator is to always keep beam in the storage ring itself, at a high current, with a good lifetime.

The movement of particles through the particle accelerator is controlled by electromagnets (magnets that derive their magnetic strength from the amount of current running through them). Therefore, the ring is made up of hundreds of dipole magnets, also called bend magnets, because their purpose in the ring is to bend the beam at small angle increments to create the circle of the storage ring. In addition to the bends, the ring also contains quadrupole magnets, sextupoles following most of the quadrupoles, and two octupoles. As the beam travels, it tends to defocus, spreading out in space. Quadrupole magnets focus the particle beam to prevent it from losing its shape. Depending on how it’s oriented in space, a given quadrupole only focuses in one directions, horizontally or vertically. Therefore, quadrupole magnets often work in pairs, with one focusing in one direction, and the second focusing in the other. The role of the sextupole magnets is to provide chromaticity adjustments.

To control the amount of current in the magnets (and thereby controlling their strength), the laboratory uses choppers. Without the choppers, each magnet would receive a voltage of 70V and would not be adjustable. The power draw for each chopper can be adjusted from the control room, giving operators the freedom of a completely adjustable ring. When it was built this was revolutionary for a particle accelerator. Sometimes choppers can blow in the ring, like fuses, and it is the operator’s job to go down into the tunnel and replace them.

In addition to magnets, CESR also has four superconducting RF cavities; two in the west, two in the east. Just like the prebunchers, the job of the RF cavities is to keep the stored beam in the ring. Without RF, the beam would lose its energy almost immediately and fall out of the ring. More on this below.

CHESS Lines

Just like the particle accelerator is composed of different component parts, CLASSE is composed of different divisions: CESR and CHESS. CESR is the division that oversees the particle accelerator and makes sure it is running correctly. CHESS stands for the Cornell High-Energy Synchrotron Source. The current primary function of CESR is to produce high-quality X-rays that can be used by scientists for their research. CHESS maintains the facilities where scientists can utilize the X-rays produced by CESR and serves their research needs. The primary objective for CHESS, and therefore CESR, is to provide continuous and smooth X-rays, which in turn depends on having a continuous and smooth beam for as long as possible.

CHESS has its own terminology, which the CESR operator often has less exposure to. CHESS currently houses 12 possible beamlines, or stations, where scientists can do their research. Seven are currently funded and available for users.

Each beamline consists of a cave and a hutch, though there are five caves, and each one is connected to at least two hutches. The hutch names are based on which insertion device (wiggler for ID1, undulators for IDs 2-7) feeds the beam, as well on the experiment being run. E.g. The PIPOX beamline is at ID3A —check. hutch. The ID3A hutch is named that because it receives beam from the ID3 (insertion device 3).

For safety reasons, no one is allowed inside the cave while X-rays are being produced. Unless there is leaking radiation, which the lab will work to address, the hutches should be safe to enter. Because the X-rays need to travel down a very specific axis in their beamline, CHESS is always monitoring beamline positions and correcting deviations in real time. The CESR operator likewise performs these corrections during his/her shift.

Other Systems

Vacuum:

The machine must always be under vacuum. The CESR vacuum runs at 10-9 torr, while the Synch vacuum is at 10-5 torr. This is because if things like dust particles or chemicals are present in the beamline, the positrons and electrons will collide with them and it will be impossible to maintain a beam. Keeping the CESR vacuum low is much more important than the synch vacuum, because the beam is stored in CESR, and the worse the vacuum is the shorter the stored lifetime. The beam in the synchrotron is only there for a few milliseconds before it reaches the end of its life and splatters away or is injected into CESR, so a vacuum pressure of 10-5 torr is good enough for the purpose it fulfills.

There are various types of pumps set up throughout the ring, but the most commonly referred to ones are the distributed pumps and the lumped pumps. The distributed pumps are always turned off during a machine access because they require the dipole field in order to work, but the lumped pumps stay on in protect mode. The lumped pumps have three modes: start, protect, and off. If a lumped pump is in start, it can only stay that way for a limited amount of time, and it should be watched, because there is a real possibility of it catching on fire. If it’s in start that means there are no protections on it, there is no way for it to signal that it has completed its job and does not need to draw as much current. That is why they are always in protect mode, unless a member of the vacuum group wants to work on improving the vacuum of a specific section of the ring using a lumped pump. Unlike the lumped pumps, the distributed pumps need the CESR dipole magnets to be on before they can be powered up.

Because it takes a long time to reach target vacuum pressure throughout the accelerator, accelerator components are divided into vacuum sections. The LINAC, synchrotron and CESR all have their own sections, which are illustrated on the vacuum map in the control room. Each section can be sealed off from the rest of the machine using gate valves. Gate valves form a tight seal at either end of a given section, allowing you to lose vacuum in that section but not in the rest of the accelerator. This is an essential feature for making repairs to the machine if there is a problem in a certain part of it.

As CESR operator, you are concerned with the state of vacuums throughout the LINAC, synchrotron and CESR. Monitoring programs and alarms inform you when a particular vacuum isn’t working. If a vacuum is constantly unable to reach target value, you might be dealing with a vacuum leak, a physical deformity which compromises the sealed vacuum environment. Leaks need to be investigated and resolve by the vacuum group; alert them if you think you see a problem. More frequently, a vacuum momentarily loses pressure, but then restores itself. This is called a vacuum burst, and you need to wait and see if it is just a glitch or an actual problem. Sometimes you also see a vacuum trip; in this case something has caused a vacuum pump to turn off, and you need to turn it back on from inside the control room.

Cryogenics

The cryogenics systems involve everything that is cooled with liquid nitrogen (LN2) and liquid helium (LHe). This means the superconducting wigglers and the CESR RF, as well as several elements in the CBETA project such as the ICM and the MLC. There are three “Cryo engines,” named A, B and C, though usually only two are in operation at any one time. These engines pump the necessary helium and nitrogen to the equipment that uses them. LN2 comes from tanks that get refilled every couple of days, while LHe is generally recycled. There is a dewar (a double-walled flask of metal or silvered glass with a vacuum between the walls, used to hold liquids at well below ambient temperature) that holds spare LHe, so if more is necessary for cooling it is pulled from the dewar. When it boils off into its gaseous form it is trapped and cooled again using the engines, and then restored into the dewar.

RF

Each part of the machine has its own RF: the Linac RF, the Synchrotron RF, and the CESR RF. There are three RF cavities found inside the synchrotron, and four inside CESR. The two different RF systems are referred to as Synchrotron RF and CESR RF, respectively. It is really important to recognize that these are different RF systems, and not to conflate the two. Confusingly, people around the lab will often just say “the RF” without specifying which RF system they mean, most frequently when they are talking about the CESR RF. Context is key in these moments. The RF system associated with the LINAC is not frequently discussed (with the exception of the prebunchers).

All of the RF systems behave in similar ways, in that they consist of a wave adding or subtracting energy from incoming particles, but the CESR RF is the only one that is superconducting (kept at a low temperature with the use of liquid nitrogen and helium), and that affects both species of beam at the same time.. The CESR RF cavities are located at the ends of the East and West flares in the ring, near quads 8E and 8W, respectively

Because particles lose energy in the form of synchrotron radiation as they travel around the synchrotron and storage ring, there needs to be a way to replenish energy to the system. This energy-addition is performed inside RF (radiofrequency) cavities. Radiofrequency just describes the type of waves used inside these cavities to impart energy to the travelling particles (the physics of how this works won’t be described here). The cavities themselves are hollow spaces which have a specific shape and size to control the movement of the RF waves inside of them. The sources of the RF waves are large devices called klystrons. Klystrons amplify the RF signals prior to their use inside the cavities. The RF waves are passed from the klystrons to the accelerating cavities using waveguides, which are hollow, rectangular ducts through which waves can travel freely.

The Synchrotron RF is unique in that it can hold both species of beam, but not at the same time. Conditions have to be flipped in the synchrotron to accept the correct species before injection. This can be done either manually by flipping three switches on a rack, or by running a script on a Linux machine. Unless there is a special request from the RF group for some sort of testing, the operators always run the script. There are three RF cavities for the synchrotron, located in the ring at the L1, L2, and L5 locations. The L3 and L4 locations still exist, but the RF cavities there have been taken out of commission.

Wigglers and Undulators

If I accelerate an electron in a perfectly straight line (like in the LINAC), it will simply move faster and faster until it reaches the speed of light. If there were a frictionless linear accelerator of infinite length, it would travel infinitely without losing energy. However, if the electron beam is forced to turn (as in the synchrotron and CESR), something different happens: the electrons begin releasing large amounts of energy in the form of radiation. This released energy is known as synchrotron radiation, because it was first discovered in synchrotron accelerators. Part of the radiation is in the X-ray region, and that is what is captured in CHESS beamlines. It turns out that the more the electron beam is forced to bend, the higher-energy are the X-rays produced. This is what wigglers and undulators seek to do: they are narrow passages built into the travel path lined with dozens of small bending magnets that force the beam to oscillate rapidly back-and-forth. The high-energy X-rays that result from this rapid oscillation are immediately channeled into CHESS beamlines to be used for research.

CESR currently houses 13 wigglers and two undulators. 12 of the wigglers are actually not in use during regular CHESS running; they are only used for low energy experiments, and CHESS always runs at high energies. The undulator is only in use during CHESS running. There is a current plan to build more undulators: it is part of an update project called CHESS-U, which will happen in 2018.

The Control Room

This section contains information that every operator must know while running the machine. Familiarity with the racks, oscilloscopes and screens in the control room, and what each one does, will come with time and exposure. In the meantime, here is a list of procedures, frequent trouble alarms one hears in the control room, as well as a list of software commands an operator is expected to know and use.

Energy, Current, Lifetime

The essence of the CESR operator job is running and maintaining the positron/electron beam inside the electron storage ring. How do we monitor these beams?

First of all, understand that there are two beams stored inside the storage ring: positrons and electrons. Both have two primary properties: lifetime and current. The energy defines the regime in which the beams are run; current CHESS running is done at 6.0 GeV (gigaelectronvolts). Outside of CHESS running, however, researchers have the option of running the machine at 2 GeV, or low-energy conditions for specific experimental purposes. There is a written procedure for how to switch between the two energy levels.

Independent from the set energy, each beam has an independent associated current level, measured in mA (milliamps). This is essentially a measure of how many particles there are in the beam, with all of their individual currents added together to produce the total current. A simple rule-of-thumb is that higher currents produce higher-quality X-rays, so CESR scientists are always trying to run at the highest currents possible. As of right now, we are running positron beam at 50 mA; however, in the past they have been run at 100 mA, and at higher currents as well. The target current is ultimately the result of beam conditions, and this can change from run-to-run, and even from day-to-day (when conditions aren’t stable).

Stored lifetime means the amount of time a beam will stay in the machine without refilling. For example, if the lifetime is 8 hours, if we did not add more beam to CESR in 8 hours, all of the beam would be lost. The beam decays exponentially.. So if there is a lifetime of 8 hours with 200 mA of beam in the machine, after 4 hours there would be 100 mA in the machine, but by that point the lifetime could have improved to 12 hours, so the beam wouldn’t drop to 50 mA until 6 more hours had passed. Of course, the less beam there is in the machine, the less intense the x-rays provided to CHESS are, and past a certain point they don’t even see x-rays, so we must find a good balance of lifetime and filling time.

Bunches, Buckets and Trains

So what is the actual beam? It is not uniform like a laser. Particles are not spread out evenly throughout, like a uniform stream, instead they are “bunched up” into discrete pulses (like train-cars in a train). These formations are called “bunches,” so we describe the beam as being composed of some number particle bunches. The bunches are regularly spaced from each other, and their regular spacing is described in terms of time. So in CESR, for example, we say that the bunches have “14 ns (nanosecond) spacing.” That means that as one bunch passes a point in the storage ring, the next bunch after it will follow 14 ns later. This time spacing is not arbitrary, but has to do with fundamental features of the machine (more specifically, the selected oscillation frequency of RF waves used to accelerate the bunches). More generally, the complex timing pattern that controls bunch-spacing and injection is known as the timing system.

Bunches that are spaced closely together are collectively referred to as “trains”. So, for example, electrons in CESR are currently organized into three trains with a 4ns spacing, with each train having 16 individual bunches (for a total of 48 e- bunches in the ring). These numbers are subject to change, however, so there is no need to memorize them.

If bunches are organized along a timing-pattern of 14 ns, it means that you are allowed to position a bunch every 14 ns – not that you are obligated to do so. In other words, each 14 ns spacing is a time slot that can potentially be filled or left empty. This time slot is referred to as a “bucket,” and we talk about “filling a bucket” or “leaving it empty.” The total number of available buckets is determined by the timing system, but at any point there are many more unfilled buckets than filled ones in the machine.

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(A graphic showing positron [red] and electron [blue] bunches. Electrons are clearly organized into three distinct trains, each with 16 bunches represented by vertical lines. Each bunch has its own associated current, represented by the height or fill level. The small “stubs” visible at the base of each train represent unfilled bunches.)

Because each bunch is a collection of particles, each bunch has its own current (in mA). This current is referred to as the per-bunch-current. In the image above, the current of each bunch is represented by the bunch’s vertical height (the y-axis is in mA). The total height (or total amount of current) allowed to each bunch is called the total fill level and is controlled by the CESR operator (look under CSR FILLINGS). Ideally we want to keep the fill level as low as possible, while still reaching the total target current of 120 mA. The reason we want to keep the fill level low, instead of just raising it arbitrarily high to induce faster filling times, is that higher per-bunch-currents lead to a less stable beam. Why? Since bunches are made up of particles, and all of these particles have the same charge (negative in the case of electrons, positive for positrons), they experience repulsive-forces and want to fly apart. (If you recall, quadrupoles and other focusing magnets keep this from happening). The greater the current density in the bunch, the greater the repulsive-forces, the less stable the bunch overall.

Injection and Tuning

When we talk about injection, we talk about adding electrons to electron bunches and positrons to positron bunches stored in the storage ring. We have to do this because the beams decay over time, and we are trying to maintain a certain current level. We can only inject one species at a time, either positrons or electrons, because only one species can exist within the LINAC and the synchrotron, where particles travel before they are ready to be fed into the storage ring. Because new electrons (or positrons) have to be added to a bunch at the exact moment that bunch is passing the injection site, injection timing is a complex accomplishment.

As things currently stand, there are two modes of injection: manual and automatic. Positron and electrons beams are not maintained the same way. Positrons are continually “topped off” every few minutes using an automated algorithm. We do this to keep the positron current constant, and when plotted it resembles a straight line. The program controlling positron injection is called the “topoff” program, and it is the operator’s job to make sure it is behaving correctly. Electrons on the other hand are refilled manually every two hours; it is the operator’s job to interrupt the CHESS run and refill electrons. We talk about “refilling” electrons and “topping off” positrons. Sometimes the beam in the storage ring is completely lost due to some technical issue; safety features are activated and we lose all current in CESR. This is known as a total beam-loss. When a total beam-loss occurs, we have to refill the beam, and we say we are “filling from scratch.” In addition to a total beam-loss, it is also possible to have a partial beam-loss, when only some amount of current is lost from either species. Depending on the cause, this might be easily recoverable during a regular topoff or refill.

The reason we can’t automate both electron and positron injection is that only positrons or electrons can move through the LINAC and synchrotron at a time. r. We talk about the “conditions” in the LINAC and synchrotron: they are either “electron conditions” or “positron conditions.” Changing from one to the other is referred to as “switching conditions.” Since it’s impractical to constantly switch conditions during a CHESS run, we automate positrons, and let electrons decay over a given length of time. The essential problems are the waveguide switches in the synchrotron and the positron target in the LINAC.

Because our machine is so flexible, we can change many elements in the machine to improve injection quality. This is called tuning, and it is at the core of what operators do to ensure good injection. This can get a little confusing, but tuning should not be confused with something called the vertical tune and horizontal tune, which are important parameters used to control the beam. The vertical and horizontal tunes, not to get too complicated, are just set values that control how the beam moves through the machine. (The beam oscillates in both the x- and y-directions, hence the need for both vertical and horizontal controls). The tunes, therefore, are something you can control while tuning. You can tune the tunes.

A Regular Week…

A year at CESR is divided into different periods. The most prominent are CHESS Runs and long downs. During CHESS runs (the lab’s bread and butter), CESR is providing X-rays to scientists that come to use them from all over the world. There are two CHESS runs per year. Downs are periods when the machine is turned off for maintenance and repair. Any construction projects also take place during downs. There are two long-downs, a Winter Down and a Summer Down. In addition to CHESS Runs and Downs, there are also shorter periods called CESR Machine Studies (MS), during which CESR scientists have access to the particle accelerator to complete their own research. These take place normally 1-2 weeks at the beginning and end of each CHESS Run. There are also short CHESS Machine Studies during which beam alignment takes place. A yearly calendar can always be found posted right outside of the CESR control room.

An average week of CHESS Running begins on Wednesday at 12:00 P.M. and continues until the following Tuesday at 7:00 A.M. Every Tuesday the machine is turned off for a short “Tuesday Down” during which maintenance work is carried out. It is the CESR operator’s job to prepare the machine for the Tuesday Down, during which the ring has open access. The machine is then turned back on sometime Tuesday afternoon, and undergoes overnight “processing,” during which the beam is allowed to run without CHESS users to make sure everything is still working. At noon on Wednesday the next week of CHESS running begins.

Long downs are a long duration of open access, and machine study periods resemble CHESS runs, except that the machine conditions are different and serve the needs of specific physics experiments.

Safety

Safety, as anyone will tell you, is the most important aspect of the operator’s job. Because CESR is a radiation facility, making sure irradiated parts of the particle accelerator are not accessible to staff and scientists is essential. A system of interlocks is used to prevent people from entering radiation areas during machine operation. An interlock is simply a device that, when triggered, indicates that the security perimeter surrounding radiation areas has been breached, forcing an immediate beam-dump and puts a stop to all radiation-emitting activity. There are both gate interlocks and light-beam interlocks protecting the ring. Gates are small doors that cause a trip when they are opened, and light-beam interlocks are invisible shafts of light positioned at foot-level that trip if you walk through them. Gates are positioned at entry-points to the ring, while light-beam interlocks are positioned all throughout the ring. Interlocks break the ring up into sections, making it possible to secure parts of the ring section-by-section.

Interlocks all have special boxes that allow you to bypass them if you have the right key. For example, during Tuesday Downs, we have something called White Key Access during which you can use white keys to walk around the tunnel, bypassing the interlocks (the machine is turned off at this time). White key access is useful for short downs, when you want to go down into the ring, but don’t want to open it for general open access.

Open access is characterized by having the interlock system turned off, allowing workers to go into the ring without a special key. Once an open access has ended it is crucial to make sure no one is left in the tunnel before turning the machine back on. To do this, an operator performs a search-and-secure operation, walking around through all parts of the ring and checking each to ensure no one is still working there. Interlocks are switched on during the search-and-secure so that no one else can enter or move through the ring without alerting the system. As you walk around the ring, you need some way of “checking off” each section being searched to indicate that is clear. This is accomplished using “reset boxes,” which don’t actually do anything except serve as proof that a given area has been searched and rendered safe. The operator activates the reset boxes using a white-key as he proceeds along his search. Although the reset boxes don’t actually do anything, the machine cannot be turned on until every single reset box has activated.

Procedures

Preparing White Key Access

  1. Bump out the stored beam:
    • Turn off the CESR RF using the inhibit knob.
  2. Run turnoff_mag (also runs gun down)
  3. Turn off LINAC
  4. Turn off LINAC HV AUTH
  5. Turn CESR RF to “Inhibit” (if you didn’t do this to knock the beam out)
    • Double check with John Reilly that he turns off the CESR RF high voltage. (Putting CESR RF into “Inhibit” mode does not actually turn off its high voltage). Also note: sometimes one of the CESR RF transmitters (East/West) will be required to remain on. Double check that John Reilly is aware of this.
    • Sometimes, if John Reilly isn’t in the building, it is up to the CESR operator to turn off CESR RF high voltage. This can occur if shutdown occurs before 8:00 in the morning, or if John is out sick.
  6. Close Beam Killer gate valves
  7. Turn off Synch DC (once the turnoff_mag program has announced you are ready to do so)
  8. Turn off QUAD EMI PS (once the voltage has dropped below 1)
  9. Remove Operator’s Key (this also closes the beam killer gate valves if you forgot the step above)
  10. Push the panel release button, open the panel door and remove the first white key

Extra Steps for Tuesday Down (Open Access)

  1. Pull Master Operator’s Key and open the White Key Panel
  2. Turn SRF to low power (after completing turnoff_mag)
  3. Manually turn off SEC 2, POS OUTPUT, EL OUTPUT gate valves
  4. Lock out group magnet power supplies for CESR and Synch
  5. Wait for the radiation survey to be completed (John Stillwell or Tom Dugan)
  6. Flip the interlock switch down to break all interlocks and begin open access.
  7. Announce over the PA: “Attention: Open Access has begun. I repeat: Open Access has begun. Please return all white keys at your earliest convenience.”

Bumping Out the Beam

  1. Dial up WXF BUMP HV (E+ TRANSFER → WXF BUMP HV)
  2. Turn bump on (the 3rd black button under “E+/E- Injection”)
  3. Slowly run master bump up.
    • If some trains aren’t falling out, you can push the LINAC Bunches on and off (blue buttons) or cycle through patterns in inj – they are the same thing
  4. As the beam current decreases, the falling-out rate may also decrease; just increase the bump to speed the process along.
  5. If the master bump is at maximum and the beam is still not falling out, start raising one of the individual bumps
  6. Turn bumps off when you’ve reached your desired current.

Green Key Access

  1. Turn off LINAC HV
  2. Turn off GUN HV
  3. Turn off LINAC HIGH VOLTAGE AUTH
  4. Press LS1 Key Cover Release (You’ll need a 2nd Person)
  5. Pull out your own GRN KEY and be the last to put the GRN KEY in
  6. Before putting in the last GRN KEY, press “PERIM RESET,” place the key in, then press “PERIMETER SECURE”
    • If the perimeter is not reset before putting the last key in (e.g. a gate is still open), the interlock will break when you push the last key in and you will have to search the area.
  7. Put the last key in, close box
  8. Turn on LINAC HV AUTH, run the GUN up (panel pushbutton), press LINAC reset/enable, turn on LINAC.

Entering LS1 while the CESR beam is up is a controlled access, so you will need a second person. If it is after hours, call the CHESS operator. This access is important for adjusting the prebuncher, but refrain from adjusting it unless the waveform itself is warped. If it is simply “throbbing,” barometric pressure is the likely culprit and no adjustment is necessary (you just wait for the pressure to return to its previous value).

Resetting a Broken Interlock During Green Key Access

  • Note: You cannot remove the Master Operator’s Key (and therefore any white keys) to set the Reset Boxes during Green Key Access, since this would trip the primary perimeter and dump the beam, if there is beam in the machine. Luckily, there is a second Operator’s Key immediately to the left of the first one for explicitly this scenario. You can use it to reset any reset boxes in the Green Key area. Be careful not to leave the green key area though (LS1/Gun cage)! If you do, the beam will be dumped and you’ll have to reset more interlocks, reset boxes and use a regular white key to do that.

Resetting a Broken Interlock During White Key Access

  1. If an interlock is broken, you will hear a loud unmistakable whooping alarm.
  2. Walk over to the interlock display panel (CRA.07.02 - .04) and look for a flashing yellow light in the Radiation Chain. The blinking yellow light corresponds to the BROKEN INTERLOCK. Read the label above the blinking light (e.g. CLEO MEZZ.) to identify the location of the broken interlock.
  3. You should reset the interlock immediately so that it can be reactivated for further security. Take the Operator’s Key. Recharge it by pushing it into its circuit, and then push its arm into the adjacent MAIN RESET pocket (small hole to the immediate left) to actually reset the interlocks.
  4. Next, go on the PA system and announce: “Whoever broke the interlock in [“broken area”], please pick up the beamphone on line [1-10]. Someone should respond to your call. Ask them if they broke the interlock, and whether or not they have a white key. If they do not, offer to bring them one.
  5. If you cannot find the person who has broken the interlock, you must search the area where the interlock was broken.

Turning on the Beam

  1. Make PA announcements at 1:00 hour, 0:30, 0:15 and 0:05 minutes to the end of OPEN ACCESS.
  2. Check the watervlv program. Make sure there are no “closed valves.”
  3. 15 minutes prior to turning interlocks on (entering “white-key access” mode), unlock the Synchrotron and CESR Bus Magnets. Make the following announcement first: “Attention: we would now like to begin unlocking the Synchrotron and CESR Bus Magnets. I repeat, we would now like to begin unlocking the Synchrotron and CESR Bus Magnets. Questions or Objections, Line XX.” If no objections, go ahead and unlock magnets. Make sure there are no locks on the group lockout box first. If there are, page the owner of the lock.
  4. At the set time, recharge the Master Operator’s Key, push in the “arm” to reset the interlocks, and turn all interlocks on.
  5. Proceed to take a white key and perform the Search & Secure. Once Search and Secure is completed, look at the white key panel and ensure that all the white keys are in place. Push “Perimeter reset” and look at the radiation panel to ensure all of the perimeter gates are closed.
  6. Push in the Operator’s Key.
  7. Push “perimeter reset” and wait for the green light.
  8. Push “bypass reset” and wait for the two red lights.
  9. Push “perimeter secure” and wait for the green light.
  10. Push the reset buttons on the Radiation Chain.
  11. Make sure all the distributed pumps are “enabled.”-- Unless specifically closed by the vacuum group, they should stay enabled through an open access.
  12. Manually open all closed gate vales, El & Pos Snouts Output and Sec 2 gate valves.
  13. Enter Linux command: turnon_mag. (Make sure to check watervlv before doing this!) Wait for the program to run up the magnets.
  14. Turn the CESR RF to “Run.” Watch for the High-voltage to come on in the display.
  15. Turn on the Synch RF AC Power and wait until the display comes on indicating full power.
  16. Turn on LINAC HV AUTH.
  17. Press LINAC RESET/ENABLE and wait for the ready light to come on. Make the following announcement: “LINAC HV is coming on, there should be no one in the radiation area. I repeat, LINAC HV is coming on, there should be no one in the radiation areas.” Press the RED button to turn the LINAC on.
  18. Once the “turnon_mag” program is finished running, do a magnet loop by entering the Linux command magnet_loop.
  19. Begin species injection.

Saving Sets into Route

  • A saved “set” refers to a specific combination of variable conditions that have been tuned for running. “Route” is a program that runs whenever conditions are loaded. Saving a “set” into “route” means ensuring that the set you have just saved will be reloaded even if you’ve altered elements.
  • Sets can be saved without putting them into route. Sometimes it is desirable to test if a given set of conditions is actually good before putting in permanently into “route.” There is also a way of restoring previous sets if current sets are not working, or other reasons.
  • Sets are always identified with numbers.

To save a set and place it into route

Enter save lin, save syn, or save csr Linux commands. Then enter Linux command route. Enter “ch” to change the linac and synchrotron sets in route (for the condition you are in: poslin and possyn).

Enter “up” to update CESR sets in route (this is generally pmbinj).

Switching Routes

  • Enter route. Type in “sw” for ‘switch’ and hit enter.
  • A list of different route files appears. Highlight the one you want to use and press the middle button on the mouse to copy/paste it into the command line and hit enter.
  • Quit route.
  • Do a magnet_loop

Entering Power Save Mode

  • Enter: “turnoff_mag
  • Turn off EMI Power supplies (Quad Busses) after dipole power reading decreases below 1.0
  • Turn off Synch DC Power
  • Inhibit RF and put both West/East Transmitters into Standby (Go down to WEST RF Area/East RF Area LOE)
  • Put SRF to Low Power
  • Run down solenoids
  • Do not pull any keys.

Turning only the Synchrotron On (Not CESR – needed for Machine Studies)

  • Follow procedure points 1 - 10 for Turning on Beam.
  • Open any closed Synchrotron, LINAC and Snout gate valves.
  • Unlock synchrotron magnets and make sure they are all powered on.
  • Dial up “SYN MAG CUR” and set it to 0 (if it is not already 0).
  • Turn on the DC Ready button, and turn it ON.
  • Press the red button and holding it press “Disable,” “Enable” and if there is a set value, backdate the command to enter that value. If there is no set value (e.g. after a database refresh), enter 43673
  • Turn ON the AC. Check the display to make sure it comes on.
  • Make an announcement that LINAC High-Voltage is coming on. Turn on the LINAC.

Preparing for Magnet Bypass Mode from Machine Operation

  1. Bump out the stored beam (follow Bumping Out the Beam procedure)
  2. TURN OFF LINAC HV and LINAC HV AUTH
  3. TURN OFF GUN HV
  4. Turn CESR RF to “Inhibit”
  5. CLOSE Beam Killer Gate Valves
  6. TURN OFF SYNCH AC/DC
  7. MAKE SURE that the MAGNET BYPASS KEY is in! Only a limited number of people are authorized to use the magnet bypass key.
  8. Remove the OP’s KEY, open the white key cover and pull white keys.

Preparing for Magnet Bypass Mode from Open Access

  1. Make PA announcements at 1:00 hour, 0:30, 0:15 and 0:05 minutes to the end of OPEN ACCESS.
  2. Check the watervlv program. Make sure there are no “closed valves.”
  3. 15 minutes prior to turning interlocks on (entering “white-key access” mode), unlock the Synchrotron and CESR Bus Magnets. Make the following announcement first: “Attention: we would now like to begin unlocking the Synchrotron and CESR Bus Magnets. I repeat, we would now like to begin unlocking the Synchrotron and CESR Bus Magnets. Questions or Objections, Line (1-10).” If no objections, go ahead and unlock magnets. Make sure there are no locks on the group lockout box first. If there are, page the owner of the lock.
  4. At the set time, recharge the Master Operator’s Key, push in the “arm” to reset the interlocks, and turn all interlocks on.
  5. Proceed to take a white key and perform the Search & Secure. Once Search and Secure is completed, look at the white key panel and ensure that all the white keys are in place.
  6. Push “Perimeter secure” and look at the radiation panel to ensure all of the perimeter gates are closed.
  7. Push in the Operator’s Key.
  8. John Barley will turn the key for Magnet Bypass
  9. Depending on what is necessary, either do a turnon_mag or manually turn on whatever magnets John asks for

Recovering from Magnet Bypass Mode

  1. RETURN all white keys.
  2. RESET the perimeter.
  3. CLOSE the white key cover.
  4. PUSH in the OP key.
  5. PRESS perimeter secure and machine key bypass.
  6. RESET the CESR Ready Chain.
  7. TURN ON Synch AC/DC
  8. OPEN all vacuum gate valves.
  9. OPEN RF gate valves (E1/E2/W1/W2)
  10. TURN ON LINAC HV AUTH
  11. TURN ON LINAC (don’t forget to make an announcement!)
  12. TURN ON GUN HV (Gun Runup button)
  13. TURN CESR RF to “Run” mode and wait for the RF to recover
  14. READY to inject beam.

Frequent Trouble Light Alarms

#15 – LINAC Vacuum Alarm

Check “Vacmon” monitor. Look if any vacuum has a pressure larger than 10-6 Torr. If this is the case call the vacuum group. This is a very serious alarm

#1 – Undprotect not running.

Check to see whether or not this is a glitch. Look at the “Watch Prog” display and see whether the “undprotect” program is running (GREEN) or not (RED). If it is not running, enter command: service_restart undprotect

Enter command service_restart libera_ioc but only if the beam is not lost. If the beam is lost, go to “und interlock window” and click “reset interlock.” Then open the killer_gate valves, turn on CESR RF by typing in rest_cesr_rf.

#19 – EWC #3.

Go to website: https://biotech.alc.emcs.cornell.edu/. Find the appropriate alarm. Call KATE MILLER or Leila Aboharb.

#39 – Synchrotron Magnets OFF/Linac HVPS On

Goes off if you turn the LINAC on before running turnon_mag.

This alarm might also occur if the machine is already running and only the synch magnets shut off. In this case:
  • Go to CRA.05 and follow the instruction sheet:
  • Use simcon to set SYN MAG CUR to 0
  • Turn on DC BIAS READY LIGHT, then turn DC BIAS ON
  • Go back to simcon and check syn e offset (SYNCH MAGNET → SYN E OFFSET → 27). It should be at the target value.
  • Change SYN MAG CUR value: push and hold the red “function” button, press DISABLE, ENABLE and then put in the target SYN MAG CUR value (39700, High Energy State; 19700 Low Energy State).
  • Turn on AC Power (after pushing READY button).

# 46 – Machine Key Bypass

You can generally ignore this alarm. Check the white key panel, see which key has a loose connection, and ascertain that the bypass reset light is lit. Inform Mike Ray of the faulty connection in case there is a problem within the circuit.

#52 – Water Leak 4th Floor

Go up to the 4th floor and check all over for water leaks. If one is found, call Kate Miller.

#58 – Intloc not working. Intloc is a safety-interlock relay computer program, which is tied to alarm #58. It is an important program, so if this alarm goes off it is certainly something to make a note of. There are two possible reasons as to why the alarm would be activated:

1. The program is running slowly at some relay juncture, so that the time between relay resets exceeds a certain allotted limit, thus activating the alarm. If this is the case, the alarm should simply reset. (Again, although the alarm resets, system programmers would still like to know that the program is running slowly, so it is a good idea to make a note of it in the elog).

2. The program really isn’t running, which is a serious issue. In this case it would fail to reset. Call Mike Forster or Laurel Bartnik.

#60 – CLEO Mezzanine Interlock & Reset (gray key area reset) (when interlock switch is ON) Remove a gray key: area reset panel. Pull the GRAY/GREEN reset key, reset interlocks with the key arm, go out and do all the reset boxes, press perimeter reset and then perimeter secure.

#71 – Make-up Water Alarm, 65 or 85 degree.
Listen to the text-talker to see which of the four water pump is in “make-up”, and then check the sentry program window. Pull up newin. Go to “machine stat” and open a record of the pump in question. Select a 1 – 2 week timeframe and try to determine if the alarms are occurring more frequently than usual (i.e. are the lines bunched up significantly over a short duration or evenly spaced).

If makeups do not appear to be occurring more frequently than normal, wait for the makeup period to end (which will be noted on sentry) and then enter service_restart sentry to reset the alarm timer. If you do not restart the makeup timer, 1) the alarm will recur periodically because it will always be “over time,” and b) you will not have an accurate length if it DOES go into makeup again.

If the makeups DO appear to occur more frequently than usual, or you get a series of makeup alarms in over a short interval in one shift (i.e. the system keeps going into makeup), or if the makeup timer does not stop – you are probably dealing with a leak in the water system. Call Kate Miller or Mike Ray.

A “makeup” refers to an event in the water system, where a reservoir is refilled from an external water supply. If the reservoir takes longer to fill than a certain allotted length of time (e.g. 13 min), the makeup alarm will be triggered. The reason it may be taking longer might be a leak, hence the need for alarm.

#87 – #96
Group of CRYO Alarms. Call Dan Sable or Colby Shore asap. Cryogenic issues are always high priority.

#98 – #105
Call Building Facilities: Kate Miller or Leila Aboharb or Rich Gallagher

Frequent Text-talker Announcements:

Distributed ion pumps in wrong state - This actually does not refer to the high/low energy state of CESR, rather to the high-low voltage state if the DIPs Low voltage state is the preferred state. Use command dip_low to change the voltage to low; dip_high changes it to high.

Dipole not set - This message appears when changing conditions and indicates that the NMR, line dipole reading is too far off its intended target value. The intended target value is for pnmr(3), and is usually 2009.3 at high energies. Use commands dipole_raise_1 or dipole_lower_1 to change it is necessary. See What to do if… section.

Gun Filament not right - The Gun filament value is off the target value. To deal with this, first pull up the Gun Filament value history in newin → GUN MON CON → FILAMENT E, I, P (3 panes). Try to determine if the filament value dropped suddenly or decayed gradually over a length of time. Take stock of the situation and call the Linac expert (Bob Meller – if he is unavailable call Jerry Codner or John Reilly).

Injection CESR set incompatible polarity - This means that the LINAC set does not match the CESR set (e.g. ellin in the LINAC but epxray in CESR). If there is beam in the machine, this immediately leads to a beam dump.

L1/L2/L5 Downstream/Upstream Vac Trip - This can only be corrected by taking an access the tunnel and restarting the pump controller in the affected section. If we are in the midst of CHESS Running, immediate access is not necessary: we can live with it until the next down. Don’t forget to make a note in the Elog saying that it needs to be fixed.

Low power in KM1. Turn LINAC off and on - Follow the Textalker, and turn the LINAC off, restart the inj program (“service_restart inj”), and then turn the LINAC back on. – Call Bob Meller if it doesn’t work.

Prebuncher tuner at limit - This means the prebuncher tuner is at a mechanical limit. There is no need to react immediately (See: GREEN KEY ACCESS) – it could be reacting to outside barometric pressure (you can check ‘newin baro’). There is no need to call anyone if things are still running, but make a note in the Elog that it should be fixed. React more actively if you get the “Prebuncher amplitude is not able to reach its amplitude save set value” Textalker, in which case one of the prebunchers needs to be adjusted.

Linac … vacuum too high - This is probably the result of a vacuum burst. Check the LINAC display panel. The particular element which experienced the burst should show a long white bar, or if the vacuum has recovered a short white bar followed by a gray bar; this event can go in the ELOG shift summary. Simply reset the LINAC and resume regular operation.

No Synch Beam - You sometimes hear this during injection. It means that the beam in the synchrotron is not being picked up by the monitoring system. This can happen for several reasons: one is that the synch beam disappears for a particular bunch pattern but will recover once the inj program automatically switches to a different pattern. Another reason is that a synch capacitor has blown, messed up the beam orbit in the synchrotron, and the beam is not actually getting through. If you get this alarm you must investigate whether you do or do not have beam, and why. After 5 seconds of no synch beam however, injection is automatically turned off by the program, so if you recover the beam you must turn CESR injection back on. This also sometimes happens with the first topoff once the topoff program is started. For some reason it does not enable the synch beam before injecting for the first time. Turn on synch beam manually.

Undulator radiation approaching limit for this shift - The undulator contains hundreds of small permanent magnets. High radiation weakens these magnets, so we have set a limit to how much radiation they can be exposed to within an eight hour period.

Wiggler Insulation Vacuum - Indicates that the pressure for one of the wigglers may be off from the correct value. To check what the vacuum values are, go to CESR Online Main Page → CESR Documentation → SC Wiggler Magnets → Wiggler Data from Ring. A page opens with a list of values for different wigglers (updates every 30 sec). Look under the Insul VaccCCG column, which displays pressures for the different magnets. Values should be around 10-8. If they are significantly different from that power (e.g. 10-5), something is wrong and you should contact Dan Sabol.

XBUS Crate Failed - If this announcement occurs ONCE, it most likely means that the crate signaling was slow and you can disregard it. If this announcement occurs REPEATEDLY in quick succession, it probably means that a crate has indeed failed. Notify the CHESS Coordinator for further instruction and make a note in the Elog. (An XBUS Crate is a crate that contains interface cards. Everything in the tunnel is controlled by crates. A crate failure means that communication has been lost with one of the crates).

Linux Commands

*commonly used commands

anevent: calls up a record-keeping program used to look at the performance many machine elements over time. It is extremely useful as an analytic to see how machine components were behaving around an event of interest (e.g. Q49W at the time of a beamloss, etc.).

bumset w: sets/resets the west transfer bump. This is useful when the bump fails to set during switching conditions (bumset fails). (for electrons the command is bumset e – not currently needed).

cesr_info: provides a list of shortcuts for frequently used paths in Linux.

* chess_corr_auto: launches chess autocorrections, a program that tracks chess x-ray positions and corrects them in real time. This program is continually running in the background during normal operations. – not currently in use - 11/4/19

* chess_det_mask: opens a toggle program that allows the CESR operator to mask/unmask specific chess beamline detectors. Normally the CHESS operator calls the CESR operator and asks him/her to mask/unmask a detector.

chess_corr_manual: manually corrects chess beamline positions. Done if the auto-corrections do not seem to be doing enough. – not currently in use – 11/4/19

comet_v: Comet records conditions in the machine, holding approx. the most recent 500 turns of the beam. This command opens up the record; it can in particular be useful as a way of determining whether the RF system was responsible for a beamloss.

countdown:used when topoff is suspended. It gives the time interval necessary for chess_corr_auto to run.

* cxc: opens the “cxc” program, which displays a collection of interlocks belonging to various components, e.g. the west CESR RF. This program can be used to diagnose problems and reset them.

dip_control: changes the state of the vacuums between “high” and “low.” [dip_low or dip_high are alternative immediate commands that allows you to skip a step.]

dipole_raise_1: increases the value of the NMR, line dipole reading by a small incremental amount once. Its complementary command is dipole_lower_1.

d_xrf_east or d_xfr_west: runs d_osc (shows the transfer elements).

* dump_cesr_beam – dumps CESR beam by gently running down the RF

* gunproc: opens gun processing programs

ldinit:

lrfp: displays the history of linac trips.

makeup_reset_(65deg/cesr85/cryo/linsynexp) – resets the timer on the makeup for the chosen system

* magnet_loop: turns on dipole magnets. Needs to be completed after magnets are turned on; also needs to be run to remove hysteresis.

* newin: opens the program Newin: it contains hundreds of elements, showing the history going back several years. The time scale can be compressed to an hour, or expanded to months or years. Used frequently for many things such as checking the refill times of water tanks to determine if a leak is occurring, checking the vacuum pressure in specific locations, checking whether filament power for the electron gun has been decaying over time, etc.

* newin alarm: opens newin and displays plots containing elements that have most recently been included in a text-talker alert. Be aware that not all text-talker alerts will show up with this command.

newin_list: lists the existing shortcuts for frequently used newin plots. For ex. newin waterstat plots the “makeup” or refilling times for each of the water tanks used by the lab.

* operate_linac_window: opens a Linux window that contains the standard commands to run the Linac. Usually always open on main computer in the control room.

* operate_chess_corr_window: opens a Linux window that contains the standard commands for CHESS running without steerings.

operate_chess_window: previously constantly used for chess running. Opens a Linux window that contains the standard commands for CHESS running with steerings. Not currently in use.

operate_cesr_window: Opens a Linux window that contains the standard commands for a CESRTA run. Rarely in use.

post_loss: enter this command whenever there is a beamloss. Edit (put in your initials at a minimum), save and quit. Enter ‘y’ in the terminal window to post the loss record to Elog. Check to make sure it did in fact post.

* rest_cesr_rf: if an undulator magnet trips off the RF

rest lin: short for “restore linac set”. This command allows you to restore a previously saved linac set. The command typically takes the form of “rest lin” followed by the number of the set you wish to restore, e.g. “rest_lin_150433”.

rest syn:short for “restore synchrotron set”. This command allows you to restore a previously saved synch set. The command typically takes the form of “rest syn” followed by the number of the set you wish to restore, e.g. “rest syn_150434”.

* sctcmd: (scalar to command), the magnet clock gets hung. Must push “abort magnet clock.” There are two distinct, harsh “whe-oo-whe-oo” sounds. One is at a higher frequency, and this one is no big deal. Another one is slower and indicates a real problem with the magnet clock. In either case, entering this command is fine to do.

service_restart sentry: restarts the sentry programs, clearing old data. Generally done to enable changes done in the sentry or alarm limits file.

service_restart vacmon: restarts the vacmon program.

shortcuts op – provides a list of linux commands frequently used by operators

* topoff_pos: opens the topoff program, used to automatically topoff positrons during regular running.

tt_lock_acq – stands for tune tracker lock acquisition. Locks to the tune trackers to the T1B1, allowing us to read the vertical and horizontal tune

* turnoff_mag: command turns off synchrotron AC power, turns off the separators, the CESR magnets (dipole, quads, L0/L3, canting) and runs down the Quad PS: look up at the watchprog screen and wait for the voltage to fall below 1V, and then physically turn off the quadrupole magnets (CRC_XX).

* turnon_mag: turns on synchrotron DC power, CESR magnets (dipole, quadrupole, L0/L3, canting) and the separators.

vacon: program for manipulating the vacuum pumps. You can turn vacuum pumps on/off, change energy state, etc. If the key under the vacuum map was turned to low energy, it must be turned back to high energy before all the vacuum pumps can be run back up – no longer a common occurrence.

vtuneadj – used in conjuction with tt_lock_acq – reads out the tune and spits out a text-talker warning when it freezes or drops below a certain value.


Topic revision: r4 - 11 Mar 2020, pmo42
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