Diamond Detectors for Ionizing Radiation - HEPHY

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Chapter 2 Introduction Diamond is a material with a set of very unique characteristics. It is mainly known as a gem, but also for its hardness. There is a third property that is not so well known; diamond shows extremely high thermal conductivity while it is electrically insulating. Besides that, diamond has the reputation of being radiation hard since the 1950s, but only recently this has been examined systematically using modern irradiation facilities. One eld of future applications of CVD (chemical vapor deposition) diamond could be particle detection in high energy physics experiments, where fast, radiation-hard detectors are required. The goal of the RD42 collaboration is the development of tracking detectors 1 made of CVD diamond for the LHC. The group is involved in both the ATLAS (A Toroidal LHC Apparatus) and the CMS (Compact Muon Solenoid) experiments, which are projected for the LHC. As I am aliated with CMS, I will give a short description of the possible utilization of diamond there. Fig. 2.1 shows the complete CMS experiment. Only the pink cylinder in the very center is the solid state tracking detector, containing strip and pixel detectors. While the strip detectors will be denitely made of silicon, the material for the pixel detectors could be either silicon or diamond. The reason for this diamond option is the extreme radiation in the vertex environment. Present standard silicon detectors are operable up to a uence of approximately 10 14 particles cm ,2 [2]. With this uence, the radiation defects do no longer allow meaningful measurements. The total uences of photons, neutrons and charged hadrons expected in the CMS experiment over the scheduled 10 years of LHC operation is shown in g. 2.2. z is the distance from the vertex along the beam axis, while the parameter is the radius from the beam axis. Two permanent pixel layers are planned at radii of 7 and 11 cm and a third one at r = 4cm only for the low luminosity period in the beginning of LHC operation. The photon and neutron uences are silicon-compliant. The charged hadrons, however, most of which are pions with a momentum below 1 GeV c ,1 , are a challenge, which can be accomplished with diamond detectors. 1 position-sensitive detectors with good spatial resolution 6
CHAPTER 2. INTRODUCTION 7 Figure 2.1: The CMS experiment at CERN. Not only the LHC groups are interested in CVD diamond. Proposals have been submitted for using CVD diamond detectors for monitoring of heavy ion beams at GSI- Darmstadt [4] and for a research program for avertex detector upgrade at Fermilab [5]. Besides the narrow eld of high energy physics, one can imagine to produce semiconductor devices based on diamond. However, presently there is one major technical restriction. While intrinsic diamond is easily engineered to a p-type semiconductor by implantation of boron acceptors, no reasonable donor material has been found yet.
Page 1 and 2: Diploma Thesis Diamond Detectors fo
Page 3 and 4: CONTENTS 3 7 Radiation Hardness 37
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Page 9 and 10: Chapter 3 Material Properties 3.1 G
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Page 21 and 22: CHAPTER 5. DETECTOR MATERIAL COMPAR
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Acknowledgements First of all, I am
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APPENDIX A. ABBREVIATIONS AND SYMBO
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APPENDIX A. ABBREVIATIONS AND SYMBO
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Bibliography [1] Austrian Academy o
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BIBLIOGRAPHY 65 [29] A. Hrisoho, Fr
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Diamond Detectors for Ionizing Radiation - HEPHY

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