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

[Alexander Somov]

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)

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)

The trigger equation reads FCAL + 3.5 BCAL > 0.5 GeV

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...)


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
>
>
>
>