Diamond Detectors for Ionizing Radiation - HEPHY

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CHAPTER 6. CHARACTERIZATION 30 Figure 6.3: Schematics of the grounded base trigger amplier. order to cut o low frequency (1=f) noise, a miniature transformer was utilized in the prototype tests discussed in [33]. In our setup we used a simple RC combination of low and high pass, providing similar signal processing. The risetime of the amplier is specied to be < 600 ps, while the noise is stated to be ENC 1000 e + 60 e pF ,1 . Compared to the integrating charge-sensitive amplier discussed above, basically accuracy is sacriced for speed. 6.1.3 Readout Electronics The front-end electronic is very sensitive against any kind of electric inuence. Therefore, a central ground point is essential, together with the shielding of the complete setup. In the Vienna characterization station, the front-end has been packed into a coppershielded box, which is kept closed during measurement. This is also necessary as the detectors and the VA2 chip are sensitive to light. Fig. 6.4 shows a photograph of the box. During measurements, the lid is closed and the collimator with the source mounted onto it. Fig. 6.5 shows the detailed schematics of the Vienna characterization station. The diamond detector is AC coupled to the VA2 to allow dierent potentials. As the VA2 chip output stage obviously is not very powerful, a repeater card (designed by A. Rudge and the Ohio State University) is foreseen, which buers both incoming and outgoing VA2 signals. For calibration purposes, a well dened step pulse is attenuated and sent to the VA2 input over a small capacitance, injecting a charge of Q = CV : (6.3) There are two separated voltage dividers in the attenuator, because inevitable stray ca-
CHAPTER 6. CHARACTERIZATION 31 Lid (Holds Collimator and Source When Closed) Repeater Board Diamond Sample on Ceramic Support VA2 Hybrid (Covered) Trigger Detector and Amplifier Figure 6.4: The Vienna characterization station. pacitance results in capacitive rather than galvanic coupling if the division ratio becomes too high. The data acquisition and control in the Vienna setup is done using CAMAC modules and an Apple Macintosh IIfx computer. The CAMAC crate is equipped with a nonstandard Bergoz MAC-CC controller, while the Mac utilizes a Micron card to establish the connection. The detector bias voltage is provided by a commercial CAMAC HV module (Struck CHQ203A). A module built by the Ohio State University (OSU M663A) handles the VA2 triggering and readout, while a home-made CAMAC module is responsible for general control, trigger decision and calibration pulse generation. 6.1.4 Data Acquisition Software On the Macintosh computer, a data acquisition program called Diamond Station has been written in the LabView 3 environment by H. Pernegger and myself. This software controls the CAMAC modules and reads out the VA2 analog data when a trigger condition occurs. The data is lled into a histogram, collecting the signal pulse height spectrum, which is displayed online and written to disk for oine analysis. The program is also capable of automatically recording a measurement series with one detector, sweeping the bias voltage and taking pedestals before and after. In previous versions, a common mode correction (CMC) algorithm was included, which turned out to have no signicant eect except slowing down the whole measurement. Fig. 6.6 shows a screenshot of the Diamond Station program.
Page 1 and 2: Diploma Thesis Diamond Detectors fo
Page 3 and 4: CONTENTS 3 7 Radiation Hardness 37
Page 5 and 6: CHAPTER 1. SYNOPSIS 5 primarily sil
Page 7 and 8: CHAPTER 2. INTRODUCTION 7 Figure 2.
Page 9 and 10: Chapter 3 Material Properties 3.1 G
Page 11 and 12: CHAPTER 3. MATERIAL PROPERTIES 11 Q
Page 13 and 14: CHAPTER 3. MATERIAL PROPERTIES 13 d
Page 15 and 16: Chapter 4 Solid State Detector Theo
Page 17 and 18: CHAPTER 4. SOLID STATE DETECTOR THE
Page 19 and 20: CHAPTER 4. SOLID STATE DETECTOR THE
Page 21 and 22: CHAPTER 5. DETECTOR MATERIAL COMPAR
Page 27 and 28: CHAPTER 6. CHARACTERIZATION 27 6.1.
Page 29: CHAPTER 6. CHARACTERIZATION 29 and
Page 33 and 34: CHAPTER 6. CHARACTERIZATION 33 Figu
Page 35 and 36: CHAPTER 6. CHARACTERIZATION 35 300
Page 37 and 38: Chapter 7 Radiation Hardness 7.1 Ra
Page 39 and 40: CHAPTER 7. RADIATION HARDNESS 39 7.
Page 41 and 42: CHAPTER 7. RADIATION HARDNESS 41 Ca
Page 43 and 44: CHAPTER 7. RADIATION HARDNESS 43 ev
Page 45 and 46: CHAPTER 7. RADIATION HARDNESS 45 2
Page 47 and 48: CHAPTER 7. RADIATION HARDNESS 47 no
Page 49 and 50: CHAPTER 8. DETECTOR GEOMETRIES 49 F
Page 51 and 52: CHAPTER 8. DETECTOR GEOMETRIES 51 S
Page 53 and 54: CHAPTER 8. DETECTOR GEOMETRIES 53 i
Page 55 and 56: Chapter 9 Summary The possible appl
Page 57 and 58: Acknowledgements First of all, I am
Page 59 and 60: APPENDIX A. ABBREVIATIONS AND SYMBO
Page 61 and 62: APPENDIX A. ABBREVIATIONS AND SYMBO
Page 63 and 64: Bibliography [1] Austrian Academy o
Page 65: BIBLIOGRAPHY 65 [29] A. Hrisoho, Fr

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