Checking Detector Performance


A new kumac macro has been written to provide a menu interface to the low level histograms for pibeta.  The macro is called pibMon.kumac can be accessed from PAW by typing mon:
PAW > mon
 ******************* PIBETA ONLINE HISTO BROWSER *********************
 Options:    1) Histo Menu (2D and 1D)
                 2) Checklist
                 3) Autcheck Menu (1D slices)
Enter option #, or quit:  (<CR>=)
Option 1 gives a menu of detector subsystems where summary 2D plots of raw data can be viewed.
Option 2 provides a shift checklist that can be executed once per run.
Option 3 shows a similar menu of detailed 1D slices of all the 2D plots from Options 1 or 2.

The table below briefly describes all the checks from Option 2 that are done, what can possibly go wrong, how to see that something is wrong,and suggestions on fixing the problem.


Low Level Checks

Check Name Description Sample 1D Histo Problems/Solutions
CsI ADC  Raw CsI ADC values.  All histograms are empty: Check that high voltages are on. Check the trigger mask. 
A histogram is empty: Check that all high voltage is on. Check if the signal is reporting on TDC, and then go into the area to check the signal on the scope. Check loose connection of cables. 
CsI Sum  Sum of total energy deposited in CsI, written to the CsI crystal with maximum energy deposition. 
Not Applicable to CSI VETOS(>219)
Michel edge and pienu peaks should be discernable. IF there is a dip instead of a peak at Michel position, then that means the threshold of the corresponding crystal is too high. If there are lots of events in low energy part of Michel spectrum, that means the threshold of the corresponding crystal is too low. Please refer to the csi_threshold check 
CsI TDC/TDC2  Raw CsI TDC values (CsI TDC), and corrected CsI TDC values (TDC2). The latter histograms should be centered at zero and if the secondary correction is implemented, they should be symmetric. 
The position of the each raw tdc peak should be roughly at the same positon as the others.
CsI Cluster TDC/TDC2  TDC values of CsI clusters coming out of logic in the trigger branch.
Signals not present: check the cabling and TDC units. 
CsI Thresh  Clean pi->enu events. Same types of crystals should have roughly same number of hits
CsI Ped/Ped2  Pedestals and corrected pedestals. The latter histograms should be centered around zero and have smaller spreads than raw pedestals. The rms of second pedestass should be about 3. 
The peak for raw pedestals should between 0 and 300. If it goes beyond zero, then there is a positive offset; if it goes beyond 300, there is a negative offset. 
Beam ADC  ADC signals of beam counter, degrader, and target.  not many things to see when filled with all triggers. need to look at histos filled only with prompt. check the peak position, 
Beam TDC/TDC2  TDC signals of beam counter, degrader, and target. 
Should see two peaks. The big one is prompt, the second is pistop on a curve which corresponds to Michel positrons
Beam Ped/Ped2  Pedestals and corrected pedestals of beam counter, degrader, and target 
For raw peds of CAMMAC unit, if the peak is not in the range, either adjust the offset, or increase the range to include the peak. 
Target Rates  With a 9-piece target, this is a test of how well the beam is centered. One can look at file "/data/tgt_rates.html" on online PC.  N/A  Outer target pieces count more than inner target pieces: the beam should probably be re-optimized. 
PV ADC  ADC signals of individual plastic veto counters.
The minimum ionization particle peak(positron) and the proton peak should be discernible. 
A signal is not present: Check the cable connection. Check the analog signal. 
PV TDC/TDC2  Raw and corrected TDC signals for plastic veto. Raw pedestal peak should be in the range.Corrected histograms should be centered around zero and be symmetric. 
A signal is not present: Check the cable connection. Check the analog signal.
PV GM  Geometrical mean of the 2 plastic veto counters attached to the same plastic veto stave. One should clearly see the proton peak and the minimum ionizing peak. The position of positron peak, dip, and proton should be roughly at 250, 650, and 1150, respectively. A signal doesn't look right Check individual counters that go into the geometric mean. 
PV Ped/Ped2 Raw and corrected pedestals for plastic vetoes. The latter should be centered around zero. 
Ped peak is out of range:check DC offset of fan in/out. 
MWPC Wires The histogram displays the number of hits in each wire of the chamber. The histogram(chamber1 and chamber2) should be flat.  Don't even try to play with these delicate babies 
MWPC ADC  The histogram with the number of hits in each strip should be flat.  No signal:check the ADC cable. 
MWPC Ped/Ped2  Raw and corrected pedestals for the cathode strips. The latter histograms should be centered at zero. 
MWPC Noise  Running the MWPC program on a PC, one should see the peaks with barely any noise on them.  N/A 
Trigger Rates  Look at the file "/data/rates.txt" on the online PC. The number of raw triggers should not exceed 100 triggers/second.
trig2 should not lower than trig1; trig3,4,5,6 should roughly at the same rate; trig7 is half of one of them. 
N/A  Number of raw triggers is too high: increase pre-scaling factors or decrease the intensity of the beam. 
Trigger Mix  8 histograms of CsI energy sum cut on individual triggers.  see details 
Trigger TDC  Should have no jitters  If there is jitter, look at the signal on the oscilliscope, find out the reasons: 1.bad connection, 2. cross talks. 
Trigger Timing Csi-Deg
pibeta Hi, Pibeta Lo, Csi Hi, Csi Lo
The prompt peak should not bite into main spectra good timing
bad timing
refer to checking trigger timing in handbook
Beamline Magnets  Check that Setpoint is able to connect to the server.  N/A  Setpoint isn't working: look for a beam expert!
* FSH51 and FSH52 are used to adjust the beam rates.
Beam Profile  Three dimentional positions of the Pistops  At z-direction. there should be two peaks. One is degrader, the other one is target. They should be discernible. The target peak should be much greater than the degrader peak. 
Temperature/whist  On the online PC, go to "/data" directory and run whist, select '4' for 'Environment' and then select '6' for 'Water left in'. To check the temperature inside the detector, select 2(c118 in) or 0(b88). If temperature keeps going high(low), go into the area, check:1. The setting of the big AC should be at 20. the green light on the AC should flash now and then indicating it's working. 2. Exaust pipe of iceberg. 
Humidity/whist  On the online PC, go to "/data" directory and run whist, select '4' for 'Environment' and then select '19' for 'Humidity inside'. 
Disk/Tape/Archive  Check that there is room on the disk, that the tape is working OK, and that the files are being archived by LazyLogger.  N/A  How to change tape: in odbedit, type in mtape rewind
take out the tape, put in the new tape. OK 
Zero Fan-outs  Go down to the electronics, and looking at the output of the linear Fan-in/Fan-out units on the scope (use 2mV scale), average the baseline, and adjust it (if necessary) to be at zero.  N/A  Put the Beam-plug in when doing this check.Remember to check the offset of B0/B1 inside the area. 
Gas Bubbler  The gas bubbler should not bubble on the "in" tube, and should produce bubbles in the "out" tube with frequency of ~1Hz.  N/A  Bubble on the 'in' tube means an obstruction somewhere 
Crate Fans/Iceberg Make sure that the fans supplying air for electronics are on and working.  N/A  If not working, check switch positions and/or foses. 
Empty AC Water The water produced by the air conditioning unit in the electronics house should be emptied at least once a day (depending on how humid it is.  Remember there are three pans to check.
Don't drink it if it is yellow!!

A. Lebedev, W. Li, July 29, 1999.