真空康普顿探测器的蒙特卡洛模拟

摘要

真空康普顿探测器(VCD)长期以来被用于高强度脉冲伽马射线测量，该探测器具有快速、线性、响应范围宽的优点，对较大能量区间的伽马射线具有较高的灵敏度。真空康普顿探测器结构简单，包括一个发射极，前窗，后窗，圆柱型空气隔离套筒，不同的探测器设计结构以及材料对探测器灵敏度都会有影响。本论文采用蒙特卡罗模拟软件模拟当能量为1.25MeV的伽马射线入射探测器时，不同材料对探测器入射率和背散射率的影响并寻找对应探测器灵敏度最高的材料，同时研究真空康普顿探测器的结构设计包括准直器的直径、前窗的厚度和放射源与探测器的相对位置等对于探测器灵敏度的影响，得到了合理的探测器灵敏度响应设计参数和较优的结构设计。该研究结果对于新型辐射探测器的优化设计提供了理论基础和支撑.

目录

声明

摘要

Abstract

Table of Contents

Nomenclature

Chapter 1．Introduction

1．1 Structure of Vacuum Compton Detector(VCD)

1．2 Design Criteria of VCD

1．2．1 Positive Signal Approach

1．2．2 Negative Signal Approach

1．3 Scope

1．4 Methodology for Research

1．5 Photon Interaction Theory

1．5．1 Photoelectric effect

1．5．2 Compton Scattering

1．5．3 Pair Production

1．6 Thesis Outline

Chapter 2．Introduction to MCNP Code

2．1 Introduction

2．2 Input File of MCNP Code

2．2．1 Cell Card Section

2．2．2 Surface Card Section

2．2．3 Data Card Section

2．3 Summary

Chapter 3．Quantum and Backscatter Efficiency

3．1 Quantum Efficiency

3．1．1 Theory

3．1．2 MCNP Simulations and Results

3．1．3 Effect of Quantum Efficiency on VCD Design

3．2 Backscatter Coefficient (η)

3．2．1 Theory

3．2．2 Factors Affecting Backscatter Coefficient

3．2．3 Calculation of (η)on MCNP

3．2．4 Impact of (η) on VCD Design

3．3 Summary

Chapter 4．Sensitivity Analysis of VCD

4．1 Detector’s Construction

4．2 Sensitivity Calculation

4．2．1 Calculation of Q by F1 Tally

4．2．2 Calculation of flux by F4 Tally

4．3 Simulation Results

4．3．1 Sensitivity vs Collimator Diameter

4．3．2 Sensitivity vs Front Window Thickness

4．3．3 Sensitivity vs Emitter Distance from Front Window

4．3．4 Sensitivity vs Distance between Emitters

4．3．5 Sensitivity vs Gamma ray Energy

4．4 Summary

Chapter 5．Conclusion

References

Acknowledgement