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HCAL 137 Cs calibration run 05/07/2011

HCAL 137 Cs calibration run 05/07/2011. HCAL 137 Cs calibration 05/07/2011.

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HCAL 137 Cs calibration run 05/07/2011

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  1. HCAL 137Cs calibration run 05/07/2011 Yu. Guz

  2. HCAL 137Cs calibration 05/07/2011 Deviation of 137Cs currents from nominal is shown. The nominal calibration was last time restored by modifying the HV according to the result of the previous 137Cs calibration, 09/05/2011 (57 days, integrated luminosity 339 pb-1). The variation of -39%...+31% is seen in 137Cs current. A systematical response reduction in the central region, as expected. Caused not only by PMTs but partially by plastic/fibers ageing (see next slides). The HV change necessary for the correction is also shown. The HV PHYSICS and DEFAULT recipes were updated on 07-Jul. The previous recipe is kept as PHYS_MAY2011. The HV change was rather significant in the HCAL central cells, and led to a noticeable increase of the L0hadron rate compared to the end of June. Yu. Guz

  3. 137Cs vs LED Source vs LED variation 05-July / 09-May Verification of the new HV recipe. A good correspondence between expected gain change (@oldHV) / (@newHV) and ratio of LED amplitudes taken at old HV (run 94664) and at new HV (run 95215): 2 days between these measurements. LED: 09-May (91054) and 05-Jul (94664) Source: 09-May and 05-Jul A reasonable correlation between Cs and LED variations. Yu. Guz

  4. reminder: HCAL calibration 09/05/2011 HV change necessary for the correction Similar modification done on 09-May Comparison to the 16-Feb-2011 calibration when nominal gains were set (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 HV PHYSICS recipe was updated on 12-May.The old recipe is kept as PHYS_MAR2011. Yu. Guz

  5. (search for) radiation-induced effects Yu. Guz

  6. Integrator sensitivity change 2011/2009 The 104 integrator boards are installed on the HCAL rear surface, in the PMT compartment, at 1—4.5 m away from the beam, where the dose is moderate. No significant drift of the integrator sensitivities, as expected (max change ~0.4%). Yu. Guz

  7. beam spacers scintillators WLS fibers lightguide master plate PMT Radiation damage of tiles and fibers 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. row 0 row 1 row 2 row 3 row 4 row 5 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). Yu. Guz

  8. Radiation damage of tiles and fibers Reminder: 09-May vs 29-Mar (86 pb-1) 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! Yu. Guz

  9. Radiation damage of tiles and fibers 05-Jul vs 29-Mar (424 pb-1) Now the effect is better visible (note also different Z scale): ~-3…-6% in the central cells at row 0 Yu. Guz

  10. LED/Cs variation July / May The LED data taken right after the HV correction are used. It is assumed that the Cs currents at these moments exactly correspond to the nominal. Visible discrepancy between Cs and LED is seen in the central cells: consequence of plastic ageing. Yu. Guz

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