How to

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This page is based on a similar how-to page of the LEDEX experiment.

Spectrometer how-to

How to change the spectrometer angle

First, do a visual survey of the Hall to make sure nothing is in the spectrometer's path. Also, make sure you are not exceeding the minimum (typically 14 degrees) or maximum (experiment dependent) spectrometer angle.

Second, on hacsbc2, click the red "tool box" icon on the linux taskbar, as above. Choose bogies_SetSpec so that you can determine the angle and vernier setting for the spectrometer.
Bogies SetSpec.window.gif
See the window displayed to the right. Enter the spectrometer (L or R), and the angle, and you will get two options for the floor mark and the vernier. Generally choose the vernier closer to zero. Center the cameras on the desire vernier using the Move+/Move- buttons on the Hall A General Tools screen. The cameras are on the top center TV monitors, in rack CH01A05. Third, choose bogies_Left (or bogies_Right) in the tool box to bring up the bogies control screen. Click PSM enable and wait a few seconds for PSM OK to read YES. Click DM enable and wait a few seconds for DM OK to read YES.

Make sure the velocity is set to 0 and the direction is CW or CCW as desired. Click on Brake Release and wait for Brakes OK to read YES.

Click on ClampRelease, set the velocity to 700. Once you see the spectrometer start to move in the floor angle camera - you cannot see the spectrometer move in the Hall overview camera, as it only moves a few degrees per minute at maximum speed. For the left arm, to move to a larger angle, the direction should be CCW, while for the right arm CW moves the spectrometer to larger angle. The direction of the spectrometer is reversed by using a negative rpm. Watch the spectrometer motion on the cameras. When you are getting close to the desired angle, slow down to about 300 rpm. To stop, click on the Clamp Release button and the Brake button. Disable DM and PSM, and disconnect to close the GUI. Read off the floor angle mark and vernier, and input the values into the appropriate fields in the alignment section of the Hall A General Tools GUI.

How to change the momentum setting of HRS

From the HAC window, there is a P0 SET field for each spectrometer in which you can enter the desired momentum setting. To change to a lower momentum from a higher previous setting, you just need to enter the new momentum value. To raise the momentum setting, you need to cycle the Q2 and Q3 magnets first and then enter the desired momentum setting. See the instructions for the cycling procedure on the instruction sheet to the right of the white board in the counting house.

If you want to set a momentum of 500MeV/c or less, please see this document from John Lerose for special procedures.

How to change HRS-R Dipole Setting (a delicate art)

These instructions are taken from John Lerose's document. Due to the fact that there is a short in one of the coils of the right dipole there are special considerations that must be taken into account when setting it. The short imposes two limits on operational use of the magnet.

The ramp rate is limited (~0.1 Amps sec-1) in order to keep the current induced in the short low enough to ensure safe operation of the magnet. This alone makes changing the field a slow process. Once current is induced in the short, then, left to itself, that current dies off exponentially, which affects the magnetic field, with a time constant close to 20 minutes. If one ignores this 2nd factor it can take a very long time to get a stable field in the magnet.

There’s nothing, short of taking the magnet apart and fixing it, that can be done about #1 above. However, with a little patience and forethought, #2 can be dealt with fairly easily. The trick is to use the inductive coupling between the shorted and not shorted coil to bring the current in the short to zero. This is done by always overshooting the desired current change and then going back. Use Figure 1 to determine the amount of overshoot you need for a given change in current (Δi) or you can use the spreadsheet calculator.

HRS-R Overshoot.png

For example, if the right dipole is set for 0.3616 GeV/c the output current is about 126.0 Amps (with a set current of about 123.8) and the desired field is -0.13268 T. To change to +10% higher, p = 0.3978 GeV/c, should require about 10% more current or 12.6 Amps more. Instead of just typing in iset = 136.4 (123.8+12.6), do the following:

  • type in iset = 153.3 (29.5 Amps more than you think you need)
  • wait for the magnet to stop ramping
  • type in iset = 136.4 (the setting you think you want based on the previous setting)
  • Observe the field reading and its rate of change. A strip chart helps
  • make small (<1 Amp), slow (>3 minutes apart) adjustments to compensate as needed.

Re the overshoot: Figure 1 is based on a model of the shorted coil with inductive coupling to the not shorted coil. As we get more experience we may refine that. In general for bigger changes more overshoot is needed. For changes less than 3 Amps just make the change and then make small adjustments. Also remember when going down the “overshoot” really is an undershoot. Always go past and then come back.

A final note: This assumes that the current in the short was zero when you started.

How to change the HRS collimator

How to reset the quadrupoles

The reset for Q2 is simple, on the front of the power supply there are red lights on when the power supply is tripped. At the bottom of the board that has the red light there is a blue reset button. There may be more than one light on so there may be more than one blue button that needs to be pushed. Push blue buttons until all of the red lights are out. Once all of the lights are out, lower the large lever on the lower right side of the power supply and lift it back into position. this will reset the Q2 and Q3 power supplies locally. For Q1, it's simpler : there is a large sign in the back of the Q1 equipment rack on the power supply balcony that says the blue reset button is here. you press the button and the magnet resets.

How to cycle the power on the NMR meters

HALOG entry 186341 by J. Segal: Sometimes the NMR meters need to be power cycled. Most likely when the meters do not respond to GPIB commands. To check if the meter is responding one can try to change the units on the NMR GUI. It's the GUI you get to from the "FIELDS" button and selecting "D1 NMR". Try changing units from "MHz" to "Tesla". If the units on the display change, the meter is responsive and does not need to be power cycled. If the units do not change it would be good to power cycle the meter.

  • The AC Power Switch for the Left Arm is hareboot17, port 8.
  • The AC Power Switch for the Right Arm is hareboot27, port 8.

(Username and password for IOC reboot are available in the counting house).

Halog entry 188657 by E. Brash: The IOC reboot is generally straightforward, but we had some problems getting the NMR to lock. I had some success with just setting the DAC manually to an appropriate value, and then turning the auto search on once it got close. I found that the following worked pretty well:

Right arm -> DAC=2400 Probe=B Left arm -> DAC=1319 Probe=B

How to reboot HRS magnet IOC

Go to the hall A main menu screen.

Click "IOCS". Note that the left HRS magnet IOC's (iocha14) are accessible at http://hareboot10 and the right HRS magnet IOC's(iocha16) are accessible at http://hareboot25 (Username and password for IOC reboot are available in the counting house). Close the "Hall A IOC Systems" window.

To reboot:

  • the left HRS magnet IOC's, go to http://hareboot10 and from the pull-up menu next to iocha14, select "immediate reboot".
  • the right HRS magnet IOC's, go to http://hareboot25, click on control, select iocha16, from the pull-up menu select "immediate reboot".

After the IOC reboot, please make sure that the spectrometer-angle information is reentered into the Hall A General Tools GUI.

What/where to check VDC

VDC status can be checked on the HAC Main Control Window. High Voltages and Gas Flows are constantly being monitored.

What/where to check FPP EPICS variables

On the HAC Computer:

  • FPP Chamber High, Low and Threshold Voltages can be checked by selecting "FPP" from the "Hall A Main Menu"
  • Carbon door status can be checked by selecting "FPP" from the "Hall A Main Menu"
  • High Voltages can also be checked, and in addition controlled, from "Hall A Main Menu" - "Le Croy HV" - "Left" and selecting the FPP channels. Card 7, controls chambers 1 and 2, card 8 controls chambers 3 and 4.
  • Gas Flows for both the FPP and VDC can be checked visually at the entrance to the detector stack, if you are in the Hall, or on the Hall A General Tools GUI, if you are in the Counting House.

How to set / reset phototube high voltage

From the Hall A Main Menu on hacsbc2, click on LeCroy HV. Choose the appropriate spectrometer, and then the appropriate detector. Usually the voltages are already plateaued, and you should only need to turn HV on. All voltage numbers are in Volts.

How to reset the VDC high voltage

Bring up the HAC control window per the above instructions. In the "Miscellaneous" section, click on the "Crate Resets" button. This will bring up the "Hall A Slow Controls" window. In the bottom left and right of this window are the reset buttons for the spectrometer subsystems. Click on the relevant "VDC high voltage" reset button. You then need to go back to the main HAC GUI and reset the tripped VDC to 4 kV by entering 4 in the VDC HV window. If the VDC trips again, reset the supply then try to ramp up the voltage slowly. If there are repeated trips, call an expert.

How to start xscaler (HRS) / view the scalers

start xscaler :

  • Go to the hapc5 terminal in the middle of rack CH01A09. If it is not logged in, log in as user "adaq"
  • Type ssh adaq@adaql4 and enter the password when prompted.
  • Type goxscaler
  • Type ./xscaler

to view the scalers :

  • The simplest : login to adaq l1 as adaq
  • Type xscaler
  • Follow what it says

NB : you must be in the correct directory since there are 2 versions of xscaler : the new is ROOT GUI (the previous one is Calvin Howell's GUI)

  • Make sure that the 12V box on the screen "HRS hadron systems FPP carbon doors" are always on (HallA mainmenu, FPP button, carbon doors).

Data acquisition, CODA how-to

How to run CODA

Probably "a-onl" is already logged onto "adaql2", and the runcontrol GUI is up and running. See the adaql2 monitor in rack CH01A09. If not, see the section Cold start below. Generally adaql2 should be reserved for CODA / data acquisition. Replay is particularly resource intensive and will interfere with DAQ, but more generally nothing should be done on this machine except CODA and an ssh to bring up a halog window. To start and stop runs, push the buttons "Start Run" and "End Run". Start Run includes the sequence prestart, so prestart is not needed. To change configurations, use the "Run Type" button. If you've been running, you will first have to push "Abort" button. Choose the configuration from the dialog box, then press "Download". The LEDEX experiments generally run in the configuration SINGLES

More details about the Hall-A DAQ and trigger can be found in Bob Michaels' guide.html and guide2.html.

Cold start

See the Bob Michael's guide2 (section III, cold start)

What/where to check trigger rates

Look at the xscaler display. This should be running on the computer which sits in the second level of racks, above and to the left of the DAQ computer.

How to check if there's a problem with DAQ (data acquisition)

Usually if there is a problem, it is noticed because no data is coming in, or because the system fails to stop or start runs. Check that the ROCs (Read Out Controllers) are up and if not reboot them. For more information see Bob Michaels DAQ guide . If you are not a coda expert, it might be fastest to simply exit the coda runControl window, and then restart coda as above.

How to download and check the trigger

  • Logon to an ADAQ Linux box like "adaql1" or "adaql2" as user "atrig".
  • Run
> trigsetup
  • You will be asked whether s0 is in, if you are running in 2-arm singles mode, and then if you are in coincidence mode. For this experiment you should answer "no" to s0, "no" to 2-arm singles, and "yes" to coincidence.
  • Then you will get a screen where you can indicate the particle and its momentum for each arm. Enter the appropriate values and click the "download" button. You will recieve a message informing you that the trigger has been downloaded.
  • More details are described in Bob Michaels' page Loading and Checking the Hall A HRS Trigger.

How to check the dead time

If it is not already running, type datamon in a terminal on adaql2 in the a-onl account.

How to get the portservers

On adaql2 type : start_monitors

this will open 6 xterms with in the title on which portserver to log :

so for example to log on hatsv4 port 3 type :

telnet hatsv4 2003

Beam line how-to

How to start spot++

  • Log onto "adaql2" as user "adaq"
  • Type spot++ from any directory.

How to run a Harp Scan

Please follow the directions at the Harp Scan Page

What/where to check raster

Use spot++ as described above. Also, the raster pattern should be displayed on the Tektronix oscilloscope mounted in rack CH01B05, in the middle room of the counting house. This can give you a rough idea that the raster is on, but spot++ is needed to check actual dimensions. Also see this page for more.

Logbook, monitoring and accounting

How to bring up HAC control window

The machine which runs the HAC GUI is hacsbc2. The monitor is located in the Hall A Counting House in rack CH01A02, just above the desk. Click here to see the screen. At the bottom of the screen is the linux taskbar, in the middle of the taskbar is the "toolbox" icon. Pressing on that icon will open a menu with the following choices : vdcs_off, T2.stp, StripTool, Snapshot, etc; as shown on the picture aside. Click the entry called "Menu_HallA", or "hlamain". You can also issue the command "hlamain" from the terminal.

A sub-screen entitled "Hall A Main Menu" will appear. One of the entries is labeled "Tools". Clicking on the "Tools" button opens the "Hall A General Tools" screen, which is often referred to as the HAC window.

How to bring up the Alarm Handler

From the "toolbox" icon in the taskbar, press the "Alarm Handler" label. Alarms are indicated by a beep and the alarm handler button flashing. The color red indicates values far out of range, while the color white indicates a communication failure. Clicking on the alarm handler button will bring up an alarm handler list. A detailed list is given in the left panel, and clicking on items here brings up a more detailed list in the right panel. The alarm can be acknowledged and silenced by clicking on the button beside the alarm indicator.

You can plot time dependencies of EPICS variables

Pressing the "toolbox" icon and launch "StripTool", which enables you to plot any EPICS variable(s) versus time. To find out the name of a particular EPICS variable, click on it with the middle mouse button on the MEDM GUI.

How to bring up the Beamtime Accounting Table

  • Logon to "adaql3" as user "adaq"
  • cd to ~adaq/ACCOUNT
  • type "atable"

How to start HALOG

If no halog guis are up and running, log in as user "adaq" on any "adaq.." machine. Type halog a yellow and blue and gray window will appear Enter text in the large message area, your name in the User area, and a title in the Keywords area. Remember that experiments tend to suffer from too little documentation, not too much. Also, halog entries allow people to remotely check on the experiment progress without bothering you with phone calls. When complete, after pressing the "Make entry" button, the text in the message center to the lower right corner of the window should read 'Entry Complete', otherwise something is wrong. It often takes several minutes for entries to show up in halog. Entering graphics: Click 'Grab Screen' in the bottom button row of the halog window. The halog window will disappear, and the window the cursor is in will become the active window, its outline flashing. By moving the cursor you can select any window to be selected, by clicking on the left mouse button. You also can select an arbitrary part of the screen by holding down the left mouse button and dragging the cursor along. All the time a rectangle will flash that indicates the selected area. Releasing the mouse button will then cause this screen area to be included into the entry. It will show up as a thumbnail picture in the halog window, where you can discard it or accept it, and then make a second screen grab. The images are in GIF format.

How to fill in the shift check list

This list has to be filled in every shift... For all those who never knows where to find the informations (like me ;) by Jon Dumas. Click here (format .doc)


How to check beam charge symmetry ?

Use qasy. Instructions can be found at

What does the data structure look like?

Please see the data structure page.

What/where to check target temperature and pressure

The target temperature and pressure is displayed on the target GUIs running on cryotarg as well as on the camera monitors on the shelves above the computers. Look at the camera monitor labeled "Control Rack". It displays the temperatures for the three loops on three white temperature controllers, with loop 1 at the top and loop 3 on the bottom. Ask the TO for help if you can't find the temperature or it doesn't make sense. The adjacent camera displays target pressures.

How to use the online analysis tools for the polarization transfer experiment

Online Run analysis:

  • Login to one of the adaq machines as user adaq, if you do not know the password ask the shift leader or check the counting house whiteboard for the list of accounts and current passwords.
  • Type goonlana, this will take you to the online analysis directory.
  • To start the Analyzer type: “analyzer”.
  • Type .X replay.C (for the left arm, the command for the right arm is .X replayRight.C)
  • At the prompt enter the run number you wish to replay. Then enter either 1 for hydrogen target replay, or 2 for helium target replay. If your target is carbon or an optics target, just choose hydrogen as your target. Next you must choose how many events you would like to replay. For online analysis do not replay the entire run, it is sufficient to replay a few thousand events.
  • After the replay has ended you should bring up the analysis GUI for each of the relevant detectors. The appropriate command is (in the analyzer):
       .X online.C+(“<configuration file>”,<run number>)

Where the configuration file names are:

   "detectorL" - For HRSL hardware and target information
   "detectorR" - For HRSR hardware and target information
   “FPP” - For the HRSL Focal Plane Polarimeter 
   “coin” - For coincidence and physics related information
  • This will bring up a GUI looking something like this:

  • Where during the experiment there will be a set of “golden” data superimposed in a different color for reference.
  • Run through all the windows for each of the relevant detectors and make sure they are all working properly.
  • If you are unsure about something please talk to a shift leader/run coordinator/E03-104 collaboration member.

How to test the raw data from the FPP

In order to test the raw TDC data being read by CODA from ROC4 (the FPP) the following steps should be taken:

  • Login to one of the adaq machines with the username adaq.
  • Go to the directory ~/ledex/Code/testfpp.
  • Run ./testfpp <run number> <root file name> <# events>
  • This will create a root file containing the data from the first # events of the requested run. The root file contains a tree with the following relevant branches:
    • slot – the slot in ROC4 which fired.
    • chan – the channel in the slot which fired.
    • data – the actual TDC value read from the channel.
    (Note that the relevant FPP slots are 6-12)
  • Use the root file created to plot the slots/channels etc. and decide if all is fine. If you are unsure please talk to the shift leader/run coordinator/LEDEX collaboration member of your choice.