P. Bruecken

CMS Hadronic EndCap Calorimeter Upgrade Studies for SLHC “Čerenkov Light Collection From Quartz Plates”

Due to an expected increase in radiation damage under super-LHC conditions, we propose to substitute the scintillator tiles in the original design of the hadronic endcap (HE) calorimeter with quartz plates. Quartz is shown to be radiation hard. Using wavelength shifting fibers, it is possible to collect efficiently the Cerenkov light generated in quartz plates. This paper summarizes the results from various test beams, bench tests, and Geant4 simulations done on methods of collecting light from quartz plates, as well as radiation hardness tests on quartz material.

CMS Hadronic Endcap Calorimeter Upgrade Studies for SLHC “P-Terphenyl Deposited Quartz Plate Calorimeter Prototype”

The Large Hadron Collider (LHC) is going to start taking data with 1033 cm-2s-1 luminosity, and reach the designed value of 1034 cm-2s-1 in 2013. The LHC luminosity will continue to improve each year, reaching to 1035 cm-2s-1 in 2023. We call this high luminosity era the Super-LHC (SLHC). Hadronic Endcap (HE) calorimeters of the CMS experiment cover the pseudorapidity range of 1.4 ≪ η ≪ 3 on both sides of the CMS detector, contributing to superior jet and missing transverse energy resolutions. As the integrated luminosity of the LHC increases, the scintillator tiles used in the CMS Hadronic Endcap calorimeter will lose their efficiency. The CMS collaboration plans to substitute Quartz plates for the scintillator tiles of the original design. Various tests have proved Quartz to be radiation hard, but the light produced by Quartz comes from Cerenkov process, which yields drastically fewer photons than scintillation. To increase the light collection efficiency, we propose to treat the Quartz plates with radiation hard wavelength shifters, p-terphenyl or 4% gallium doped zinc oxide. The test beam studies revealed a substantial light collection increase on pTp or ZnO:Ga deposited Quartz plates. We constructed a 20 layer calorimeter prototype with pTp coated plates, and tested the hadronic and the electromagnetic capabilities at the CERN H2 area. Here we report the results of these test beams as well as radiation damage studies performed on p-Terphenyl.

Quartz plate calorimeter as SLHC upgrade to CMS hadronic endcap calorimeters

Due to an expected increase in radiation damage under super-LHC conditions, we propose to substitute the scintillator tiles in the original design of the hadronic endcap (HE) calorimeter with quartz plates. Quartz is proved to be radiation hard by the radiation damage tests with electron, proton, neutron and gamma beams. Using wavelength shifting fibers, it is possible to collect efficiently the Cherenkov light generated in quartz plates. This paper summarizes the results from various test beams, bench tests, and Geant4 simulations done on methods of collecting light from quartz plates, as well as radiation hardness tests on quartz material.

Radiation damage and light transmission studies on air core light guides

This report summarizes the radiation damage and the light transmission efficiency studies done on air core light guides with three different types of reflective material: two types of aluminized Mylar and a highly reflective plastic film from 3M called Radiant Mirror Film. The variations in light transmission efficiencies of these reflective materials have been studied with respect to the wavelengths of the incident light. The light transmission with one type of aluminized Mylar, which shows better reflectivity in UV range, deteriorated 14% after 10 Mrad of /spl gamma/-ray irradiation from a 9.5 kCurie /sup 137/Cs source. Light guides with the other type of aluminized Mylar and Radiant Mirror Film do not seem to be affected from radiation, and they show superior light transmission efficiency in the visible region.

Characterization of 1800 Hamamatsu R7600-M4 PMTs for CMS HF Calorimeter upgrade

The Hadronic Forward calorimeters of the CMS experiment are Cherenkov calorimeters that use quartz fibers and 1728 photomultiplier tubes (PMTs) for readout. The CMS detector upgrade project requires the current Hamamatsu R7525 PMTs to be replaced with 4-anode, high quantum efficiency R7600-M4 PMTs. The new PMTs will improve the detector resolution, as well as the capability of removing fake events due to signal created in the glass window of the PMT. Here, we report the dark current, anode gain, transit time, transit time spread, pulse width, rise time, and linearity measurements performed on 1800 Hamamatsu R7600-200-M4 PMTs.

P-Terphenyl deposited quartz plate calorimeter prototype

Due to an expected increase in radiation damage under super-LHC conditions, we propose to substitute the scintillator tiles in the original design of the CMS hadronic endcap (HE) calorimeter with quartz plates. Quartz is proved to be radiation hard by various tests, but the light produced by quartz comes from Cerenkov process, and it is 100 times less than scintillation photons. To enhance the light production we treated the quartz plates with p-Terphenyl, and constructed a 20 layers calorimeter prototype. Here, we report the test beam results for hadronic and electromagnetic capabilities of the calorimeter prototype as well as radiation damage results for p-Terphenyl.

Post Situ neutron and gamma radiation damage tests on different quartz types

Post-Situ neutron and gamma radiation damage studies performed on seven types of quartz fibers are reported. All fibers contained quartz cores, some of which were UV enhanced. The fiber cladding was either polymer or quartz, while the buffer was either polymide or acrylite. Previous studies with electron and proton irradiation on numerous types of quartz fibers have shown different optical degradation levels. However, neutron and gamma irradiation has not been investigated for similar quartz fibers before. After 17.6 × 104 Gray of neutron and 73.5 × 104 Gray of gamma radiation, wavelength specific damage to each type of fibers was determined. It is seen that the FBP type quartz fiber by Polymicro shows the least damage due to neutron and gamma radiations.