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  本文關(guān)鍵詞： 暗物質(zhì) 二相型液氙時間投影室 PandaX　出處：《上海交通大學(xué)》2015年博士論文　論文類型：學(xué)位論文

【摘要】：眾多的天文觀測與大尺度結(jié)構(gòu)模擬都顯示有宇宙間暗物質(zhì)存在的證據(jù)。在近三十年間被稱為WIMP(弱相互作用重粒子)的粒子因其能夠匹配現(xiàn)今宇宙的暗物質(zhì)密度,在暗物質(zhì)直接探測領(lǐng)域得到了廣泛關(guān)注。在現(xiàn)今的暗物質(zhì)直接探測技術(shù)中,使用液氙作為探測介質(zhì)的二相型時間投影室技術(shù)(LXe-TPC)是目前最為主流的一項探測技術(shù)。其主要優(yōu)勢在于對伽馬本底很好的辨別排除能力,以及高質(zhì)量的事例三維重建能力。二相型液氙時間投影室的高本底排除效率源于在液氙中伽馬本底產(chǎn)生的電子反沖和暗物質(zhì)可能產(chǎn)生的核反沖間電離與閃爍信號比例的差異。目前對于液氙中的低能信號響應(yīng)模型并沒有達(dá)到可靠的精度。其中需要完善的有在低能區(qū)(幾ke V)電子反沖的光子電子產(chǎn)生率,以及對伽馬本底排除率極限的相關(guān)問題。在本論文第三章中將介紹一套小型二相型液氙時間投影室的開發(fā)與構(gòu)建,涵蓋對其真空制冷、氣液循環(huán)、數(shù)據(jù)采集和數(shù)據(jù)分析系統(tǒng)的介紹。所研發(fā)的探測器在試運行中得到了較高的能量分辨率,適合用于研究液氙中低能量的電子和核反沖信號。本論文將在第四章中詳細(xì)闡述使用該小型二相型液氙時間投影室探測低能反沖信號的過程,以及我通過所得數(shù)據(jù)構(gòu)建的信號模型。該信號模型更新了已有模型中對于低能電子反沖以及液氙中反沖分辨能力上理解的不足。測量結(jié)果對利用液氙探測器尋找暗物質(zhì)可能產(chǎn)生的電子反沖信號[1,2]起到了參考作用。同時也為下一代液氙探測器的優(yōu)化給出了方向。本論文在第五章中將詳細(xì)介紹Panda X暗物質(zhì)直接探測實驗的數(shù)據(jù)分析。Panda X是中國第一個使用二相型液氙時間投影室技術(shù)的暗物質(zhì)直接探測實驗。它坐落于擁有目前世界最低宇宙線本底的四川錦屏地下實驗室CJPL(6900多米等效水深)。Panda X一期探測器利用扁平狀的靈敏區(qū)域設(shè)計增大探測器光采集效率,力求提升對于低質(zhì)量暗物質(zhì)的探測靈敏度。本論文第五章將介紹由作者開發(fā)的名為Panda X Raw Pulse Analyser(PRP)的數(shù)據(jù)分析系統(tǒng),以及利用Panda X第一批數(shù)據(jù)對于低質(zhì)量暗物質(zhì)的分析研究。該結(jié)果排除了先前其他暗物質(zhì)探測實驗給出的低質(zhì)量暗物質(zhì)可能的參數(shù)區(qū)域[3 6]。
[Abstract]:Numerous astronomical observations and large-scale structural simulations have shown evidence of the existence of dark matter in the universe. In the last 30 years, particles known as WIMP (weakly interacting heavy particles) have been able to match the density of dark matter in the present universe. In the field of direct detection of dark matter, the direct detection of dark matter has been paid more and more attention. LXe-TPC, a two-phase time projection chamber using liquid xenon as a detecting medium, is one of the most popular detection techniques at present. Its main advantage lies in its ability to distinguish and exclude gamma background. The high background exclusion efficiency of the two phase liquid xenon time projection chamber is derived from the electron recoil produced by the gamma background in liquid xenon and the potential nuclear recoil ionization and scintillation signals produced by dark matter. Low energy signal response model in liquid xenon has not achieved reliable accuracy. Among them, the photon electron production rate of recoil electrons in the low energy region (several ke V) need to be improved. In the third chapter of this paper, we will introduce the development and construction of a small two-phase xenon time projection chamber, including vacuum refrigeration, gas-liquid cycle, and so on. The introduction of data acquisition and data analysis system. The detector obtained high energy resolution in trial operation. It is suitable for studying low energy electron and nuclear recoil signals of liquid xenon. In Chapter 4th, the process of detecting low energy recoil signals by using this small two-phase xenon time projection chamber is described in detail. And the signal model I constructed from the obtained data. The signal model updates the lack of understanding of low energy electron recoil and recoil resolution in liquid xenon in existing models. The electronic recoil signal produced by dark matter [1t2] plays a reference role. It also provides the direction for the next generation of liquid xenon detector optimization. In Chapter 5th, this paper will introduce the number of direct detection experiments of Panda X dark matter in detail. According to analysis. Panda X is the first direct dark matter detection experiment in China using two phase liquid xenon time projection chamber technology. It is located in the CJPL(6900 multi-meter equivalent water depth of Sichuan Jinping Underground Laboratory, which has the world's lowest cosmic ray background at present. Panda X first stage detector uses a flat sensitive region design to increase the photoacquisition efficiency of the detector. In chapter 5th, a data analysis system called Panda X Raw Pulse Analyser/ PRP, developed by the author, is introduced. And the analysis of low mass dark matter using the first batch of Panda X data. This result excludes the possible parameter region of low mass dark matter given by other dark matter detection experiments.
【學(xué)位授予單位】：上海交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：P145.9

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本文編號：1510502