How to calibrate shower and preshower with cosmics

Procedure to calibrate shower and preshower with cosmics

1. Set the T6 threshold to -20mV using command " theshold_BB -s BB_Sh -20mV" on any adaq@adaql* machine.

2. Take a run with ps6=1 for about 500k events.

3. Replay the Bigbite run

4. go to "adaq@adaql6:~/e06014/shower_calib/" location where you can find two scripts - one for shower and one for preshwer

5. Run the scripts "ser_sh_hist.C" for shower and "ser_ps_hist.C" for preshower.

4. The output of the histograms is stored in ./ps/ and the HV adjustment factors are stored in ./adj_BB/adj_sh_XXXX.dat and ./adj_BB/adj_ps_L_XXXX.dat and ./adj_BB/adj_ps_R_XXXX.dat

5. Look at the histograms first and make sure all the fits are good. If there are any bad fits then find out the rough mean value of the peak and use following procedure to make changes in the adjustment file.

 -- For shower, calculate the adjustment factor ( 120/peak_value) and set it in the file for that particlular channel.
 -- Do the same thing for preshower if the fit is bad. Preshower adjustment factor = 240/peak_value
 

6. Once both the adjusment files are ready then copy them to adev@adaql3:~/slowc/HV_HALL_BB/adj_BB/ folder.

7. Go to the above location in adev@adaql3 account and and run following commands to adjust the HV

  -- For shower: " hv_adj.com BB_SH  adj_sh_XXXX.dat" 
  -- For preshower: "hv_adj.com BB_PS_L adj_ps_L_XXXX.dat"  and "hv_adj.com BB_PS_R adj_ps_R_XXXX.dat" 
 

8. The HV is automatically updated once this is done. Save the HV file from the HV GUI.

9. Repeat the procedure by taking another cosmic run abd check to see if the ADC peaks are aligned. If not then perform the same procedure again. Usually it very close after 1-2 iteration.

10. Contace Kalyan or Yawei if there are any questions.