1 Yu. Guz HCAL status 22/06/2011

2 Yu. Guz HCAL 137 Cs calibration The 3 rd run in 2011 was performed at the technical stop, May-09. Two source passages, one right after another, both at PHYSICS HV – stability can be checked (turns out to be at ~0.3% RMS) 22/06/2011 New PHYSICS HV recipe prepared. Standalone LED runs (with 11 kHz flashing) old (#91054) and new (#91268) PHYS HV.

3 Yu. Guz Reminder: HCAL 137 Cs calibration 29/03/2011 Comparison to the 16-Feb-2011 calibration (45 days, integrated lumi 9.1 pb-1). The gain variation -22%...+8% seen. The HV change necessary for the correction is also shown (-12V…+40V). Not a big gain variation, the HV correction was not applied. 04/05/2011 HV change necessary for the correction

4 Yu. Guz HCAL 137 Cs calibration 09/05/2011 Comparison to the 16-Feb-2011 calibration (82 days, integrated luminosity 95 pb-1). The gain variation -41%...+22% seen. A systematical gain reduction in the central region, as expected. The HV change necessary for the correction is also shown (-46V…+106V). This is significantly more than 29-Mar (only 9 pb -1, previous slide). The gain variation is not negligible. The HV PHYSICS recipe was updated on 12-May. The old recipe is kept as PHYS_MAR /06/2011 HV change necessary for the correction

5 Yu. Guz Source variation vs LED variation. The following data samples used. LED: 29-Mar-2011 (run 88329) and 09-May-2011 (run 91054) (same HV) Source: 29-Mar-2011 and 09-May-2011 (same HV) A reasonable correlation seen between Cs and LED variations (41 day between the measurements) 22/06/ Cs vs LED, 09-May vs 29-Mar

6 Yu. Guz A good correspondence between expected gain ratio / and ratio of LED amplitudes taken at old HV (run 91054) and at new HV (run 91268): 3 days between these measurements. Note much better Δ(Cs)-Δ(LED) correlation than at the previous slide. 22/06/2011 check of the new HV recipe

7 Yu. Guz LED signal studies 22/06/2011 In the next few slides: 1)dependence of LED amplitudes (gain) on luminosity 2)medium-term and long-term stabilities LED/PIN ratios used; 11 kHz is always ON

8 Yu. Guz22/06/2011 ratio “3∙ kHz” / “ramp + 11 kHz” The 11 kHz do not completely saturate the gain dependence. The difference is bigger than in ECAL (?) Fill 1865, savesets: /hist/Savesets/2011/LHCb/CaloDAQCalib/06/12/CaloDAQCalib T root / /hist/Savesets/2011/LHCb/CaloDAQCalib/06/12/CaloDAQCalib T EOR.root

9 Yu. Guz22/06/2011 ratio “3∙10 32 ” / “3∙10 32 ” The stability over 12 hours looks fine. Fill 1865, savesets: /hist/Savesets/2011/LHCb/CaloDAQCalib/06/13/CaloDAQCalib T root / /hist/Savesets/2011/LHCb/CaloDAQCalib/06/12/CaloDAQCalib T root

10 Yu. Guz22/06/2011 ratio “4∙10 32 ” / “3∙10 32 ” The gain is still not completely saturated even at 3∙10 32 Fill 1871, savesets: /hist/Savesets/2011/LHCb/CaloDAQCalib/06/16/CaloDAQCalib T root / /hist/Savesets/2011/LHCb/CaloDAQCalib/06/16/CaloDAQCalib T root

11 Yu. Guz22/06/2011 ratio “3∙10 32 fill 1883” / “3∙10 32 fill 1795”. The 1 month variation is significant. Fill 1871, savesets: /hist/Savesets/2011/LHCb/CaloDAQCalib/06/21/CaloDAQCalib T root / /hist/Savesets/2011/LHCb/CaloDAQCalib/05/20/CaloDAQCalib T root

12 Yu. Guz (search for) radiation-induced effects 22/06/2011

13 Yu. Guz 13 HCAL anode currents after beam dump 22/06/2011 After beam dump Fill After the beam dump, the HCAL HV was ON during ~40 minutes, with DAQ not running (no 11 kHz pulsing). [Apart from leaking PMTs (red dots),] there is a clear pattern in HCAL PM anode currents, similar to that during data taking. Decays by a factor of ~1.5 after 20 minutes. Observed in other fills where HCAL HV was ON after the beam dump: 1787, Probably a manifestation of induced radiation. Before beam dump

14 Yu. Guz This could be seen in the comparison of 137 Cs calibration results before and after certain data taking period (in 137 Cs calibration, responses of every single scintillator tile are determined). 22/06/2011 Radiation damage of tiles and fibers beam PMT spacers WLS fibers light guide master plate scintillators row 0 row 1 row 2 row 3 row 4 row 5 The hadronic shower maximum lays ~ within the tile row 0; the dose in the row 5 is much less. Radiation damage of scintillator tiles and fibers can therefore manifest itself as a decrease of relative response of upstream rows (0, 1) with respect to row 5.

15 Yu. Guz22/06/2011 No visible regular pattern in the comparison of two consecutive source passes of 09-May Testing the procedure: 09-May run2 vs run1, no beam in between Radiation damage of tiles and fibers

16 Yu. Guz22/06/2011 a % decrease in the central area in rows 0, 1 and maybe 2. Only a small effect (if present at all). To be followed in further source runs: ~300 pb -1 between 05-Jul and 09-May! 09-May vs 29-Mar (86 pb -1 ) Radiation damage of tiles and fibers