Amplitudes Adjustments

We need to:

• correct OM HVs to obtain desired mean of 1 p.e. charge distributions
• calculate thresholds values from mean of 1 p.e. charge distributions and pedestals

Find Pedestal Values

It is carried out the following run:

• OM HVs are OFF
• Non filtered data (FADC track length is 1024)
• Program trigger

It is processed by the following steps:

• cd macros/cluster_init
• root -l -q 'pedestal_init.C("[full_path]/raw.events.[sdc].root", [verbose 0 or 1])'

The script gives an output like:

Master 192
 0    0.7
 1    6.0
 2    0.3
 3    4.8                                                                                                    4    1.6                                                                                                    5    9.8
 6    4.3
 7    3.2
 8   -4.2
 9    9.8
10   -1.8
11   11.4

So, it is necessary to repeat execution of the script for all masters and copy and paste their output.

Find means of 1 p.e. amplitude distributions

To do it the following run should be carried out:

• OM HVs are ON
• Non filtered data (FADC track length is 1024)
• Program trigger

It can be processed by the following steps:

• cd macros/cluster_init
• root -l 'pe_noise_calib_ampl.C+("[path_to_datarun/]", [season], [run], [cluster])' - it processes file extr.events*, fits 1 p.e. distributions by gauss + exponent and produces file ampl.root (with fitted histograms) and ampl.txt (with fitted means), give output like

1 chi2 = 1.2 mean = 128.2 sigma = 44.0 pois mean = 0.0.

It is necessary to check manually the fits with chi2 >> 1 (better all histograms) and put the mean obtained manually in duplicated file ampl_v2.txt.

Correct OM HVs to get desired means of 1 p.e. amplitude distributions

For new clusters in 2019 means of 1 p.e. amplitude (charge) distributions are mostly equal to 18 (90). The desired values are the same. But a lot of channels have amplitude less than 18 (bugs in Sheifler's program).

• root -l 'hv_correction2018.C("[path]/charge_v2.txt", "[path]/hv_it1.txt", "[path]/raw.config.root")' - it calculates the new HV values from current HV and current 1 p.e. means in terms of a charge increases twice if HV changes to 123 V.

The output hv_it1.txt file contains previous, corrected HVs and their differences (3 last columns):

  1   1   1      1     16.6    1330    1390      60
  1   1   2      2     15.4    1403    1471      68
  1   1   3      3     15.1    1342    1412      70
  1   1   4      4     17.3    1791    1846      55
  1   1   5      5     17.2    1322    1378      56

The corrected HVs are messaged to the Main Program developer, he carries out new run (see previous section). It is processed by this script. And procedures are repeated until all the means of 1 p.e. distributions will equal the desired values.

It is necessary to compare new HVs installed in a cluster (maininfo of the new run) with recommended values by void check_HV("[maininfo]", "[hv_it1.txt]")

Calculate threshold values

When pedestals and means of 1 p.e. distributions obtained we can calculate filtration, low trigger and high trigger threshold values in FADC codes.

It is necessary to take into account two points:

• trigger thresholds in codes Thr_codes = (Q_mean / 5.25) * (Thr_pe / 1.25) + Pedestal_codes
• filtration threshold doesnt have smoothing. So we should use Thr_codes = (Q_mean / 5.25) * (Thr_pe / 1.25) + Pedestal_codes

The value 1.25 was obtained from Lukas's work.