1 / 15

Attenuation length and PMT gain ratio study of the TC bars

Attenuation length and PMT gain ratio study of the TC bars. K. Fratini for the TC group INFN-Genova. Outline. The aim of this study is the evaluation of the attenuation length and the PMT gain ratio of the TC bars as a function of the time: two slightly different methods

ciqala
Download Presentation

Attenuation length and PMT gain ratio study of the TC bars

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Attenuation length and PMT gain ratio study of the TC bars K. Fratini for the TC group INFN-Genova

  2. Outline • The aim of this study is the evaluation of the attenuation length and the PMT gain ratio of the TC bars as a function of the time: • two slightly different methods • the analysed data are taken in the following days: • 01/10/2008 14/11/2008 16/12/2008 • 31/10/2009 07/11/2009 30/11/2009 21/12/2009

  3. attenuation length and gain ratio evaluation-1 • Paolo’s TICPLamEff TASK, for each bar: • log(Qout/Qin) vs z plot with errors • z is calculated from the time difference measured by the 2 PMTs • Fit of the previous plot and extraction of the attenuation length value assumin v_eff = 14.8 cm/ns • The fit range is equal to .75*z range Qin Qout 0 z log(Qout/Qin) = (tin - tout)v_eff/ + log(Gout/Gin)

  4. Log Charge Ratio Time attenuation length and gain ratio evaluation-2 • Alternative method • Log(Q1/Q2) vs t plot without errors • Profile • Fit on a restrected range with respect to the t range (linear zone) • v_eff depends on the bars: the values are measured on 2008 and 2009 data using Cecilia’s macro (thanks!) Not really linear behavior for all the bar, fit sensitive to the used range, equivalent data samples give results within ~1 cm (sys error)

  5. Attenuation length vs TIME: DS TC

  6. Some comments on the plots • Most of the bars show values of  above 65-70 cm. • Bars 6 and 11 show 50 cm <  < 60 cm • Few bars show a constant behaviour as a function of the time • Few bars show an increase, number 4 and 5 (?!) • Most of the bars show a decrease in  (1,2,9---> max 10cm)

  7. Attenuation length vs TIME: DS TC Measured values of the attenuation length in 2006 at BTF in Frascati 73.6±0.2 98.9±0.2 70.3±0.8 10-15%  72.4±0.1 80.0±0.2 94.0±0.3 15-20%  20-25%  ~10%  100.0±0.3 20-25% 

  8. Attenuation length vs TIME: US TC

  9. Some more comments • Unfortunately it seems that we do not have measurements for the US TC • In average US bars show lower values of . • Bars 16, 17, 19, 21 and 29 show  <= 50 cm and in particular bar 21 shows  ~ 40 cm • Most of the bars show a constant behaviour as a function of the time • Bar 24 shows a clear increase (?!) • Few bars show a decrease in  (28---> max 4cm)

  10. Gain Ratio vs TIME: DS TC

  11. Gain Ratio vs TIME: US TC

  12. Comments on the gain ratio • Most of the bars shows values reasonably in agreement with the one calculated in october 2009 on the trigger data • The HV changing is clear only in 2 out the 5 bars on wich we changed the HV setting • fits look anyway reasonable

  13. Time Resolution • It seems there’s no a clear correlation between the worse resolution in 2009 and the attenuation length behaviour as a function of the time of the bars • The worsening of the attenuation length from 40cm to 30 cm should roughly cause a 20% worse time resolution (just considering the charge ratio between 2009 and 2008 given by the exponential behaviour as a function of the ratio of photon emission point and the attenuation lenght) MC simulation for an estimate 2008 resolution 2009 resolution

  14. Conclusions • The attenuation length and the gain ratio have been evaluated as a function of the time • Methods show some strange behaviours not yet understood • In average US bars show lower but more stable values of  than DS bars. • Time resolution worsening seems not to depend on the increase of the attenuation length of the bars

  15. Some fit examples bar number 24 bar number 5

More Related