1 / 18

Joint Institute for Nuclear Research, Dubna, Russia

An improvement of radiation hardness of CMS Hadron Endcap Calorimeters under increased LHC luminosity. Joint Institute for Nuclear Research, Dubna, Russia S.V. Afanasiev, S.E. Vasiliev, I.A. Golutvin, A.M. Makankin, A.I. Malakhov, P.V. Moisenz, V.A. Smirnov

garima
Download Presentation

Joint Institute for Nuclear Research, Dubna, Russia

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. An improvement of radiation hardness of CMS Hadron Endcap Calorimeters under increased LHC luminosity Joint Institute for Nuclear Research, Dubna, Russia S.V. Afanasiev, S.E. Vasiliev, I.A. Golutvin, A.M. Makankin, A.I. Malakhov, P.V. Moisenz, V.A. Smirnov National Center for Particle and High Energy Physics, Minsk, Belarus I.F. Emeliantchik, A.V. Litomin, N.M. Shumeiko NSC Kharkov Institute of Physics and Technology, Kharkov, Ukraine L.G. Levchuk

  2. 1.479 1.392 1.305 1.566 1.653 1.305 1.392 1.479 1.740 1.566 1.653 1.740 1.830 1.930 2.043 1.830 2.172 2.322 2.500 2.650 2.868 1.930 3.000 2.043 2.172 2.322 2.500 2.650 2.868 3.000 Radioactive exposure of HE detector. Simulation of dose map (Gy per 500 fb-1) in HE Scintillator tiles of HE, which are closer to the beam, absorb the greater radioactive dose. Main aspect is to provide operation of HE calorimeters after upgrade phase II. Vitaly Smirnov - Alushta2012

  3. R (cm) Evaluation of dose in HE tiles Normal operation of HE tiles up to integral radiation level at 5 Mrad. η 2.500 2.650 2.868 3.000 Radiation dosesfor period of time, which should provide accumulation of experimental data for integrated luminosity of 500 fb-1. It means ~10 years of LHC operation. The most irradiated part of HE corresponds to η from 2.5 to 3.0 in the first few layers of HE. Vitaly Smirnov - Alushta2012

  4. Main factor of light loss Main factors of light loss with dose increase. Transmittance loss of scintillator (becomes yellow). Transmittance loss of WLS fiber. Degradation of scintillating ability. Reducing of conversion efficiency of WLS fiber. WLS fiber Kuraray Y-11. Scintillator Kuraray SCSN81 8/7/2014 Vitaly Smirnov - Alushta2012 4

  5. Scintillator irradiation Our recent measurements of scintillator + WLS fiber samples irradiated by electrons (E ≈ 4 MeV) SCSN-81 & Y11 10cm x 10cm x 0.4cm HCAL TDR SCSN-81 & BCF-91A 10cm x 10cm x 0.4cm Relative light yield 0.1 0.5 1 1 10 0.1 5 Absorbed dose (Mrad) 8/7/2014 Vitaly Smirnov - Alushta2012 5

  6. Main concept How to improve radiation hardness of HE scintillators? We decided to improve light collection from more irradiated tiles. Proposed solution: Divide tile to several strips. Each strip (width W) has own WLS fiber in the middle . Advantages: An average path of light inside a strip becomes shorter. Length of each WLS fiber becomes shorter. Losses of light are decreased. Vitaly Smirnov - Alushta2012

  7. Dependence from absorbed dose Light output from irradiated sample Degradation factor of scintillating ability Attenuation factor in scintillator and its λsc(D)attenuation length Attenuation factorin WLS fiber with length L and its λwls(D)attenuation length Conversion efficiency of WLS fiber Light output from non irradiated sample with width W Attenuation caused by optical “OR”. k transmittance loss in one “OR”. N number ofstages of optical “OR”. 8 light inputs from WLS fibers Light output from clear fiber go to megatile optical connector N = 3 stages 8/7/2014 Vitaly Smirnov - Alushta2012 7

  8. Test on electron beam Radiation source is electron beam with E = 4 Mev. An irradiation of scintillator samples + WLS fibers with electrons of doses 0.5, 1, 5, 10 and 30 Mrad. 1/16 1/8 1/4 1/2 To define light attenuation factors with different doses of irradiation. Ten copies of each type. Radiachromic dosimeters to measure absorbed dose (0.05-20 Mrad). Primary check of transparency of radiachromic dosimeters. Measurement of light yield of all samples. Measure of transmittance loss in samples. Measure of transmittance loss in WLS fibers. Vitaly Smirnov - Alushta2012

  9. Dependence of signal amplitude vs. sample width , S(W) Results were normalized to the signal from the tile (main sample) with the position of WLS fiber as in the real tile of HE. Vitaly Smirnov - Alushta2012

  10. Λsc (cm) 0.5 1 5 10 30 Absorbed dose (Mrad) Measurement results of attenuation factors Dependence of WLS fiber attenuation length λwlsvs absorbed dose Dependence of scintillator attenuation length λscvs absorbed dose λwls (cm) Absorbed dose (Mrad) Vitaly Smirnov - Alushta2012

  11. Measurement results of Jscand Jwls Degradation factor of scintillator light yield Jscvs absorbed dose Dependence of conversion efficiency of WLS fiber Jwls vs absorbed dose Jwls=A/A0 Jsc=A/A0 Absorbed dose (Mrad) Absorbed dose (Mrad) Vitaly Smirnov - Alushta2012

  12. Surfaces are cut, polished and spliced Attenuation: k4 k3 k2 k1 # of stages 4321 Inputs: 16 WLS fibers 8 WLS 4 WLS 2 WLS Introduction of optical “OR” How to minimize the upgrade process of HE megatiles? Just use as in original scheme one clear fiber from one tile. It means a necessity to combine the light coming from several WLS fibers of tile’s strips into one clear fiber. We propose to use optical “OR” scheme. kN- attenuation caused by optical “OR”. k- transmittance loss in one “OR”. N - number ofstages of optical “OR”. To Photo Detector (PD) to PD to PD to PD 8/7/2014 Vitaly Smirnov - Alushta2012 12

  13. Test of optical “OR” Photo Detector position1 L=14 cm LED L=14 cm WLS fibers Photo Detector position2 Clear fiber Scheme for measurement loss of light in optical “OR”. Three samples of optical “OR” scheme has been made and tested. The best result of light loss in optical “OR” schemeis k ≈ 0.7 Values of k ≈ 0.8 are quite affordable. Vitaly Smirnov - Alushta2012

  14. Compare of light outputs A(D) of the upgraded and standard options with equal absorbed dose Light output from non irradiated sample S(WU) and main tile S(WS) with width W kNattenuation caused by opt “OR” k transmittance loss in one “OR”. N number ofstages of “OR”. Attenuation lengthof scintillator λsc(D) Attenuation lengthof scintillator λsc(D) 8 16 4 2 1 0.5 5 10 30 Absorbed dose (Mrad) Vitaly Smirnov - Alushta2012

  15. Conclusions • Series of measurements on several sets of SCSN81 scintillator + Y-11 WLS fiber with electron beam was performed and a set of experimental results was obtained: • Dependence of signal amplitude vs. the sample width. • Transmittance loss in scintillator and its attenuation length in dependence of absorbed dose. • Transmittance loss in WLS fiber and its attenuation length in dependence of absorbed dose. • Degradation factor of scintillating ability in dependence of absorbed dose. • Conversion efficiency of WLS fiber in dependence of absorbed dose. • Possibility of combining several WLS fibers using the scheme optical “OR”. • Making several pieces of optical “OR” and measurement of transmittance loss in one optical “OR”. • Compare of light outputsof the upgraded and standard options with equal absorbed dose. • It is shown that the proposed method will allow to increase the radiation hardness of most irradiated HE tiles up to 20 Mrad. 8/7/2014 Vitaly Smirnov - Alushta2012 15

  16. 0.1 0.5 1 5 10 30 Absorbed dose (Mrad) Light yield with transmittance loss in one optical “OR” ~ 0.7 Assembly – 16 strips Main sample Measurements of light yield for all samples were performed at the same conditions. 8/7/2014 Vitaly Smirnov - Alushta2012 16

  17. 0.1 0.5 1 5 10 30 Absorbed dose (Mrad) Light yield with transmittance loss in one optical “OR” k ~ 0.7 and k ~ 0.8 k ~ 0.8 Assembly – 16 strips k ~ 0.7 Main sample Measurements of light yield for all samples were performed at the same conditions. 8/7/2014 Vitaly Smirnov - Alushta2012 17

  18. 0.1 0.5 1 5 10 30 Absorbed dose (Mrad) Area of improvement of HE radiation hardness k ~ 0.8 Assembly – 16 strips k ~ 0.7 Main sample Measurements of light yield for all samples were performed at the same conditions. 8/7/2014 Vitaly Smirnov - Alushta2012 18

More Related