1Yu. Guz

HCAL status

22/06/2011

2Yu. Guz

HCAL 137Cs calibration

The 3rd 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) taken @ old (#91054) and new (#91268) PHYS HV.

3Yu. Guz

Reminder: HCAL 137Cs 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 nece

ssary

for the co

rrecti

on

4Yu. Guz

HCAL 137Cs 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_MAR2011.

22/06/2011

HV change nece

ssary

for the co

rrecti

on

5Yu. 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)

22/06/2011

137Cs vs LED, 09-May vs 29-Mar

6Yu. Guz

A good correspondence between expected gain ratio (@oldHV) / (@newHV) 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

7Yu. 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

8Yu. Guz22/06/2011

ratio “3∙1032 + 11 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-93464-20110612T152210.root / /hist/Savesets/2011/LHCb/CaloDAQCalib/06/12/CaloDAQCalib-93457-20110612T131736-EOR.root

9Yu. Guz22/06/2011

ratio “3∙1032” / “3∙1032” The stability over 12 hours looks fine.

Fill 1865, savesets: /hist/Savesets/2011/LHCb/CaloDAQCalib/06/13/CaloDAQCalib-93487-20110613T032314.root / /hist/Savesets/2011/LHCb/CaloDAQCalib/06/12/CaloDAQCalib-93464-20110612T152210.root

10Yu. Guz22/06/2011

ratio “4∙1032” / “3∙1032” The gain is still not completely saturated even at 3∙1032

Fill 1871, savesets: /hist/Savesets/2011/LHCb/CaloDAQCalib/06/16/CaloDAQCalib-93707-20110616T121712.root / /hist/Savesets/2011/LHCb/CaloDAQCalib/06/16/CaloDAQCalib-93696-20110616T085527.root

11Yu. Guz22/06/2011

ratio “3∙1032 fill 1883” / “3∙1032 fill 1795” . The 1 month variation is significant.

Fill 1871, savesets: /hist/Savesets/2011/LHCb/CaloDAQCalib/06/21/CaloDAQCalib-94000-20110621T113728.root / /hist/Savesets/2011/LHCb/CaloDAQCalib/05/20/CaloDAQCalib-91921-20110520T005810.root

12Yu. Guz

(search for) radiation-induced effects

22/06/2011

13Yu. Guz 13

HCAL anode currents after beam dump

22/06/2011

After beam dump

Fill 1815. 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, 1795.

Probably a manifestation of induced radiation.Before beam dump

14Yu. Guz

This could be seen in the comparison of 137Cs calibration results before and after certain data taking period (in 137Cs calibration, responses of every single scintillator tile are determined).

22/06/2011

Radiation damage of tiles and fibers

beam

PMT

spacers

WLSfibers

lightguide

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.

15Yu. 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

16Yu. 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