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  本文關鍵詞：超低能量閾高純鍺探測器的暗物質直接探測　出處：《清華大學》2013年博士論文　論文類型：學位論文

  更多相關文章： 暗物質 直接探測 高純鍺探測器 超低能量閾

【摘要】：暗物質是21世紀物理學最基本的課題之一。暗物質研究對于認識宇宙的起源、演變以及物質的本源、相互作用都有著十分重要的意義。近年來，10GeV·c-2以下低質量區(qū)域的暗物質粒子直接探測成為了暗物質研究的一個焦點。 本課題作為中國暗物質實驗（ChinaDark matter EXperiment，CDEX）研究項目的第一步，使用高純鍺探測器在10GeV·c-2以下的低質量區(qū)進行暗物質粒子的搜尋。 為了降低環(huán)境本底對事例率的影響，實驗選在了世界上巖石覆蓋最深的中國錦屏地下實驗室（China JinPing underground Laboratory，CJPL），構建了包括聚乙烯、鉛、無氧銅等在內的優(yōu)良的被動屏蔽系統(tǒng)，并且采用碘化鈉探測器搭建了反康普頓主動屏蔽系統(tǒng)。為了獲得低的能量閾值，本課題以20g超低能量閾高純鍺探測器為主體建立了包括探測器及液氮灌裝系統(tǒng)，電子學信號處理及數據獲取系統(tǒng)，數據采集軟件系統(tǒng)三大部分的實驗測量裝置。經過調試與測試，該實驗測量裝置在9keV以下能區(qū)的線性偏離小于0.2%；在5keV的能量分辨率（半高寬）達到約200eV；噪聲水平（半高寬）達到約120eV，可以實現(xiàn)220eV的能量閾值。這些性能基本滿足低質量區(qū)暗物質實驗研究的要求。 為了降低噪聲和顫噪等干擾，本課題建立了基于信號時間關系以及脈沖形狀的分析方法，通過數據質量檢查、物理事例篩選及效率修正，最終得出有效的物理事例能譜。 本課題基于42天的實驗數據，采用彈性散射理論模型和最大間隙法的統(tǒng)計學方法做了仔細的物理分析，給出了暗物質截面和暗物質質量二維參數的排除線結果。暗物質粒子質量在2-4GeV·c-2區(qū)域的測量靈敏度達到了國際最好的水平。 另一方面，為了實現(xiàn)更高的靈敏度，CDEX正在升級更大質量的鍺探測器。本課題對1kg P型點接觸電極高純鍺探測器進行了測試研究，，總結了大質量探測器的一些新的分析方法，為今后開展暗物質研究提供了良好借鑒。 本課題利用20g超低能量閾高純鍺探測器系統(tǒng)地開展了低質量區(qū)的暗物質實驗研究，是國內的首次嘗試�；�0.207kg·day的有效數據，在2-4GeV·c-2的暗物質低質量區(qū)達到了國際最靈敏的水平。同時為CDEX今后的暗物質實驗研究積累了經驗。
[Abstract]:In 21th century, dark matter is one of the most basic subjects in physics. In recent years, the study of dark matter is very important for understanding the origin, evolution of the universe and the origin and interaction of matter. Direct detection of dark matter particles in low mass regions below 10 GeV 路c-2 has become a focus of dark matter research. This project is the first step of China Dark matter Experimental Project. A high purity germanium detector is used to search dark matter particles in a low mass region below 10 GeV 路c ~ (-2). In order to reduce the impact of environmental background on the case rate. The experiment was conducted at China JinPing underground LaboratoryCJPL, the world's deepest rock-covered underground laboratory in China. An excellent passive shielding system including polyethylene lead and oxygen free copper was constructed and an anti-Compton active shielding system was built using sodium iodide detector in order to obtain low energy threshold. Based on the 20g ultra-low energy threshold high purity germanium detector, the system includes detector and liquid nitrogen filling system, electronic signal processing and data acquisition system. After debugging and testing, the linear deviation of the experimental measuring device in the energy range below 9keV is less than 0.2. The energy resolution (half maximum width) is about 200eV at 5keV; The noise level (half-maximum width) reaches about 120eV, which can achieve the energy threshold of 220eV. these properties basically meet the requirements of dark matter experimental research in low mass region. In order to reduce the noise and chatter noise, a method based on signal time relationship and pulse shape is established in this paper. Through data quality check, physical case selection and efficiency correction. Finally, an effective energy spectrum of physical events is obtained. Based on the experimental data of 42 days, the theoretical model of elastic scattering and the statistical method of maximum gap method are used to make a detailed physical analysis. The results of the exclusion line for the two dimensional parameters of dark matter cross section and dark matter mass are given. The measurement sensitivity of dark matter particle mass in 2-4 GeV 路c-2 region is up to the best level in the world. On the other hand, in order to achieve higher sensitivity, CDEX is upgrading the germanium detector with higher quality. In this paper, the high purity germanium detector with 1kg P type point contact electrode has been tested and studied. Some new analytical methods of mass detectors are summarized, which provide a good reference for future dark matter research. The experiment of dark matter in low mass region has been carried out systematically by using 20g ultra-low energy threshold high purity germanium detector, which is the first attempt in China. It is based on the effective data of 0.207 kg 路day. In the low mass region of 2-4 GeV 路c ~ (-2) dark matter reaches the most sensitive level in the world. It also accumulates experience for the future study of dark matter in CDEX.
【學位授予單位】：清華大學
【學位級別】：博士
【學位授予年份】：2013
【分類號】：P145.9

【參考文獻】

相關期刊論文 前3條

1 倪凱旋;魏月環(huán);;基于液氙的暗物質直接探測[J];中國科學:物理學 力學 天文學;2011年12期

2 畢效軍;秦波;;暗物質及暗物質粒子探測[J];物理;2011年01期

3 程建平;吳世勇;岳騫;申滿斌;;國際地下實驗室發(fā)展綜述[J];物理;2011年03期

本文編號：1407822