Difference between revisions of "Beam Line"

Revision as of 16:42, 2 December 2008

E06-010 Instrumentation Requirement List: Jian-Ping Chen's memo to Kees De Jager, 08/07/08

.doc file and htm file

File of Physics/MCC experiment planner, by MCC Lester Richardson 10/21/2008

doc file page-1 and pdf file page-1, doc file page-2 and pdf file page-2

ARC energy measurement

Compton Polarimeter

HARP and HARP scan procedures

Please follow the directions at the Harp Scan Page [Harp Scan page]

Beam raster

Notes in case of Raster Power Supply Failure :

MCC will tell you which has failed -- vertical (Y) or horizontal (X). Their notation, last time I checked, had to do with the direction of
the B field. So, Y = vertical field (i.e. horizontal deflection), and X is the other way.

If the MCC cannot reset raster, here's what to do:

0. Find someone on the call list to fix it. But this often fails for some reason .... so then do 1-4 below.

1. First, determine which supply is broken and look at it to make sure you know what it looks like. Take access, find the raster,
follow it's cable to the lead-brick box containing 2 power supplies. Find the suspect bad supply. If the green LED is off (presumably
only on one supply), then indeed the supply is bad. Why ? All such failures so far are due to a 24V supply, but since we've
changed / improved this design it may or may not be so this time.

2. Find the replacement supply. It may be in EEL building room 126, or perhaps Bill Gunning has staged it somewhere else.
Note, EEL 126 is the electronics lab. It might also be in EEL 109 (or whatever is the electronics groups main lab.) If you don't
find it in EEL 126/109, you'll need to call Bill Gunning or Jack Segal.

3. What to look for: raster supplies # 5,6,7,8 belong to hall A and are matched to our raster. Do NOT use any other
power supply box. For example, if you use hall C's supplies they will probably fail (it's happened) and never mind why.
Obviously, two of the above are already deployed, the other two are spares. NOTE: #6 and 8 are "vertical" (field,
see note about MCC notation), and the other two are "horizontal" (MCC notation).

4. Make careful notes about the cabling, pull the bad supply out, restore cabling exactly as before, then call MCC while
still in the hall and make sure they can ramp up the raster to some small value like 1x1 mm. If that's ok, ramp up to
whatever maximum raster current you want. If that's ok, you are done. Exit the hall.

Beam charge monitors (BCM) and calibration procedure

Beam position monitors (BPM) and calibration procedure

How to perform a BPM pedestal run:

0. Beam current and raster should be off for this activity.

1. MCC has to follow the following procedure:

    - open BPM window "BPM Diagnostics - SEE"
    - from there pull down the "Expert Screens" and open "Gain Control"
    - for IOCSE10, use the pull down window and change from "auto gain" to "forced gain". 
    - then change the forced gain values x and y to zero.

2. Make sure CODA configuration is either Twoarm_FB" or "Twoarm_RICH". If not, follow these steps:

    - if you were running before you first have to press Abort
    - choose the appropriate configuration in runcontrol
    - select "Twoarm_FB"  or "Twoarm_RICH" 
    - Press RunTypes button in RunControl, download.

3. Set T8 prescale factor to 4 and take a run.

4. Have MCC change the BPM gain back to "auto gain".

5. Run get_bpm_pedestals.C in the root analyzer: Updated on October 26, 2008!

    - this code is now available from the onlana account on the adaq machines
    - run analyzer and type:
          get_bpm_pedestals(<runnumber>,<number of events>) with the run number and number of events you want to replay. 
    - the code should print out the new pedestals at the end 
    - post the plots and results in the Halog
    - an expert  should load the database into an editor and change them (2nd line of the [BPMx] blocks)

How to perform a bulls eye scan:

1. You need unrastered beam:

    - caution you should not do this with a target requiring rastered beam
    - use carbon, BeO, optics, or in the worst case empty instead

2. Ask MCC to steer the beam to the nominal center of the target.

3. Wait until beam is stable and have MCC perform a harp scan for 1H03A and 1H03B and a coda run during the same time,

   that's two run numbers to record. Start coda run first before asking MCC. request MCC to put ELOG entry, they should see
   all three harp wires, request plots to be saved into ELOG. record ELOG entry numbers. 

4. Ask MCC then to steer the beam to positions around the nominal center:

    - cover at least the area the raster will cover: (2,2), (2,-2), (-2,-2), (-2,2) and repeat (0,0)
    - repeat harp and coda runs for each position

5. Record Harp scan run numbers and corresponding CODA run number for each beam position.

6. Make a record of the harp scans and CODA runs in the Halog.

How to analyze the bulls eye scan:

 - detailed instructions can be found at the Analyzing BPMs website.
 - the shift crew is not expected to analysis the bulls eye scan.

Moller polarimeter and results of measurements

Scattering chamber upstream and downstream beam pipe size and window thickness

HAPPEX Luminosity (Lumi) monitors

Beam dump

Beam Recovery Procedure

After beam study or other major down time

1. Move target to Empty position, let MCC do the beam tuning to our nominal beam position (BPM values are on white board).
2. Move target to BeO/Optics position, ask for 3x3 raster (3x4 MCC units) and 2 uA beam. On the monitor, verify the beam is hitting the center of the cross-hair marked on BeO target.
3. At the mean time, do spot++ to check raster size.
4. Move target to He3 position, keep the 3x3 raster size. Ask for 2uA beam and compare the trigger rates (T1/T3/T5) with previous log (posted on the right side of the scaler monitor).
5. Keep 2uA beam, change raster size from 3x3 to 4x4 (4x5 MCC units) and then 5x5 (5x6.6 MCC units), verify that there is no change in the trigger rates. Spot++ with 5x6.6 raster is required and others are optional.
6. Once everything looks normal, change raster size back to 3x3 (3x4 MCC units). Ramp the beam to 12 uA and compare the trigger rates with previous log.
7. Continue production.

After not very short beam down (>1hour)

• Similar to the previous procedure but skipping step 5