[Halld-cal] DRAFT: daq conditions for pi0 calibration runs.

Mon Dec 14 09:52:26 EST 2015

Hi Elton,

>>> E_BCAL(6000) ~ 135 MeV (rather than 246 MeV).
>>> (correct me if I am wrong)
>> As far as the total energy, there is a factor of 2 discrepancy. Is this due
>> to adding upstream and downstream together?

The factor of 2 discrepancy is because you have to average energy
from both ends of the BCAL (this is my understanding of the BCAL
calibration, which I've learned from Andrey and Will) - let me know if
this is not right.

>> The trigger equation reads FCAL + 3.5 BCAL > 0.5 GeV
> From the spring run, the trigger equation is given by
> 10 FCAL(int counts) + 3 BCAL(int counts) > 18000 counts. Using your numbers
> we get
> -> FCAL(int counts) + 0.3 BCAL(int counts) > 1800 counts
> -> Fcal(MeV)/0.27MeV/(int counts) + 0.3 Bcal(MeV)/(0.045/2)MeV/(int counts) > 1800 counts.
> -> Fcal(MeV)  + 3.6 Bcal(MeV) > 486 MeV

Correct, this is what I ment.

Cheers,
         Alex

On Mon, 14 Dec 2015, Elton Smith wrote:

> HI Sasha,
>
> Thanks for correcting the per cell trigger thresholds. See below
>
> On 12/11/15 8:37 PM, Alexander Somov wrote:
>> 
>> Hi Elton,
>> 
>> A couple of corrections:
>> 
>> 1. The FCAL  per cell trigger threshold is
>> about 65 * 2 MeV/cnt = 130 MeV (not 18 MeV)
>> 
>> 2. The BCAL per cell trigger threshold is
>> about 10 * 0.66 MeV/cnt = 7 MeV (not 0.4 MeV)
> I forgot to convert from integral count to peak count. For the Fcal int 
> count/peak count ~ 6 and for Bcal int count/peak count ~ 15, which brings my 
> numbers close to the ones you are quoting.
>> 
>> 3. The BCAL total energy can be estimated:
>> 0.029 * 1.4 (average attenuation length correction)*
>> 1/0.88 (trigger fadc transmission window) ~ 0.045
>> MeV/count per side
>> 
>> E_BCAL(6000) ~ 135 MeV (rather than 246 MeV).
>> (correct me if I am wrong)
>> 
> As far as the total energy, there is a factor of 2 discrepancy. Is this due 
> to adding upstream and downstream together?
>> The trigger equation reads FCAL + 3.5 BCAL > 0.5 GeV
> From the spring run, the trigger equation is given by
> 10 FCAL(int counts) + 3 BCAL(int counts) > 18000 counts. Using your numbers 
> we get
> -> FCAL(int counts) + 0.3 BCAL(int counts) > 1800 counts
> -> Fcal(MeV)/0.27MeV/(int counts) + 0.3 Bcal(MeV)/(0.045/2)MeV/(int counts) > 
> 1800 counts.
> -> Fcal(MeV)  + 3.6 Bcal(MeV) > 486 MeV
>> 
>> We may want to take data with higher thresholds
>> as the beam energy is larger and the BG may be
>> larger because the magnet is switched off (some fcal
>> inner rings will be desabled for the trigger though).
>> We'll need to play around and find some optimal trigger
>> conditions for production runs (if we have any...)
>> 
> The higher energy does not actually translate into higher pi0 (or gamma) 
> energies. It rather increases the multiplicity, so we do not want to increase 
> the threshold. Of course since the magnet is turned off, the background and 
> triggering conditions are not routine and may need to be adjusted to optimize 
> the current run.
>> 
>> Cheers,
>>       Alex
>> 
>> 
>> 
>> 
>> On Fri, 11 Dec 2015, Elton Smith wrote:
>> 
>>> Hi all,
>>> 
>>> We have promised to provide Alexandre with guidelines for data taking for 
>>> pi0 calibration as input to the commissioning plan (see 
>>> https://halldweb.jlab.org/wiki/index.php/Fall_2015_Commissioning_Plan). 
>>> The present draft plan allocates about 1.5 shifts to this activity. 
>>> However, there are several shifts dedicated to "trigger runs", which might 
>>> be able to accumulate additional data. Here is a draft of run conditions 
>>> for comments and feedback.
>>> 
>>> Ideally, we can take data which can be used by both the BCAL and FCAL for 
>>> pi0 calibrations.
>>> 
>>> The main difference in the configuration for BCAL this fall is due to the 
>>> (NSB,NSA). Spring: (5,55), Fall-now (0,26). This will  have the immediate 
>>> effect of lowering the measured pi0 peak.
>>> The FCAL configuration has been changed from (NSB,NSA). Spring (3,20), 
>>> Fall-now (0,15). This will also reduced the measured pi0 peak.
>>> 
>>> Run conditions: Default settings for trigger settings with solenoid off 
>>> and current beam conditions. Highest beam current but safely away from 
>>> pileup.
>>> Nominal Beam current: 100 nA
>>> Nominal Radiator: 1.12·10-4 R.L.
>>> All detectors on, except for FDC.
>>> Inner FCAL rings removed from trigger sum based on trigger studies.
>>> Nominal trigger (same as spring configuration): FCAL_BCAL trigger .or. 
>>> FCAL only .or. BCAL only (see below)
>>>   Thresholds for the BCAL should be the same as for the spring run. 
>>> FADC250_TRIG_THR = 110 = (110-100)*0.041 MeV/count = 0.4 MeV per cell 
>>> threshold
>>>   Thresholds for the FCAL should be the same as for the spring run. 
>>> FADC250_TRIG_THR = 165 = (165-100)*0.27 MeV/count = 18 MeV per cell 
>>> threshold
>>> Data mode: 7 (75%) and mode 8 (25%) of runs.
>>> 
>>> -----------------------------------------------------------
>>> Conversion factors used:
>>> 
>>> FCAL conversions for spring run 0.27 MeV/int count. Assume trigger and DAQ 
>>> conversions about the same
>>> BCAL conversions for spring run 0.029 MeV/int count. Assume trigger = 
>>> 0.029/0.7 = 0.041 MeV/int count because of different integration windows
>>> 
>>> Trigger equation is:
>>> 1. 10 FCAL(counts) + 3 BCAL(counts) > 18000 counts  -> Fcal(MeV) + 2 Bcal 
>>> (MeV) > 486 MeV
>>> 2. FCAL(counts) > 1800 counts -> Fcal(MeV) > 486 MeV
>>> 3. BCAL(counts) > 6000 counts -> Bcal(MeV) > 246 MeV
>>> 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> -------- Forwarded Message --------
>>> Subject:     pi0 distribution without FDC on
>>> Date:     Fri, 11 Dec 2015 10:54:08 -0500
>>> From:     wmcginle at andrew.cmu.edu
>>> To:     elton at jlab.org, dalton at jlab.org
>>> 
>>> 
>>> 
>>> Hello Elton and Mark,
>>> 
>>> I ran my usually pi0 calibration plugin over field off beam data from last
>>> Spring. I attached a plot of the pi0 distribution with the FDC turned on
>>> and the FDC turned off, and we do a slightly better job with the FDC
>>> turned on, but we can clearly still use FDC off data to do a calibration
>>> if we get enough beam.
>>> 
>>> In order to plot the pi0 distribution with the FDC turned off I used the
>>> translation table command line argument to parse through all the detector
>>> systems except the FDC_WIRES and FDC_CATHODES. I ran the monitoring_hists
>>> plugin over the data along with my pi0 calibration plugin to check that
>>> there was no data in the FDC, and there wasn't. I hope that this is what
>>> you were expecting me to do, but let me know if it isn't.
>>> 
>>> Will
>>> 
>>> 
>>> 
>>> 
>
>