本文關(guān)鍵詞：中國(guó)暗物質(zhì)探測(cè)實(shí)驗(yàn)液氬反符合探測(cè)器閃爍光特性研究　出處：《清華大學(xué)》2013年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 中國(guó)暗物質(zhì)實(shí)驗(yàn) 液氬探測(cè)器 閃爍光特性 雜質(zhì)影響

【摘要】：暗物質(zhì)探測(cè)是粒子物理學(xué)、天體物理學(xué)和宇宙學(xué)的重大前沿課題之一，國(guó)際上通常采用直接探測(cè)法探測(cè)暗物質(zhì)候選粒子WIMP。中國(guó)暗物質(zhì)實(shí)驗(yàn)（CDEX）以高純鍺晶體作為主探測(cè)器，液氬作為反符合探測(cè)器介質(zhì)，探測(cè)WIMP粒子。輻射與液氬相互作用會(huì)產(chǎn)生波長(zhǎng)128nm左右的閃爍光，CDEX液氬探測(cè)器以此為探測(cè)信號(hào)。多種因素會(huì)影響液氬探測(cè)器的特性，進(jìn)而影響液氬探測(cè)器的反符合效率。CDEX實(shí)驗(yàn)需要獲得液氬探測(cè)器的特性參數(shù)，尋找相應(yīng)改進(jìn)方法。 本論文通過(guò)設(shè)計(jì)并建立液氬/氬氣探測(cè)特性測(cè)試平臺(tái)，進(jìn)行了相關(guān)實(shí)驗(yàn)。通過(guò)光電倍增管的單光電子響應(yīng)實(shí)驗(yàn)，獲得297K和77K溫度下，9357KB隨高壓變化的絕對(duì)增益值。驗(yàn)證在聚四氟乙烯表面蒸鍍TPB的效果，結(jié)果表明TPB實(shí)現(xiàn)了波長(zhǎng)轉(zhuǎn)換的功能，但由于轉(zhuǎn)換效率影響，峰位計(jì)數(shù)減少。進(jìn)行了三種純度氬氣的閃爍光信號(hào)對(duì)比，純度分別為99.999%，99.9999%和99.99999%，結(jié)果表明氬氣的純度越高，閃爍光產(chǎn)額越大。利用雙成分函數(shù)和三成分函數(shù)對(duì)閃爍光信號(hào)的平均波形進(jìn)行擬合，得到在雙成分函數(shù)情況下：快成分衰減時(shí)間11.75-15.62ns，慢成分衰減時(shí)間239.34-973.54ns，快慢成分比例0.30-0.11；三成分函數(shù)情況下：快成分衰減時(shí)間10.09-10.92ns，慢成分衰減時(shí)間564.72-1852.27ns，“中間成分”衰減時(shí)間75.37-95.09ns，快慢成分比例0.22-0.07。慢成分衰減時(shí)間隨著氬氣純度的升高而顯著提升，具有由于監(jiān)測(cè)液氬純度的可行性。獲得了99.999%純度液氬的閃爍光信號(hào)，在雙成分函數(shù)擬合情況下：快成分衰減時(shí)間19.33ns，，慢成分衰減時(shí)間211.40ns，快慢成分比例0.26。解決了因氬氣的帕邢定律導(dǎo)致的光電倍增管base板打火損壞問(wèn)題，為CDEX實(shí)驗(yàn)提供了經(jīng)驗(yàn)。
[Abstract]:Dark matter detection is one of the most important frontier topics in particle physics, astrophysics and cosmology. In the world, we usually use direct detection method to detect dark matter candidate particle WIMP.China dark matter experiment (CDEXX) uses high purity germanium crystal as main detector and liquid argon as anti-coincidence detector medium. Detection of WIMP particles. The interaction between radiation and liquid argon will produce a scintillation laser detector with a wavelength of about 128 nm as the detection signal. Many factors will affect the characteristics of the liquid argon detector. In order to influence the anti-coincidence efficiency of the liquid argon detector, the characteristic parameters of the liquid argon detector should be obtained in the CDEX experiment, and the corresponding improvement method should be found. In this paper, we designed and established the liquid argon / argon gas detection test platform, carried out the related experiments. Through the photomultiplier tube single photoelectron response experiment, we obtained 297K and 77K temperature. The absolute gain value of 9357KB changed with high pressure. The effect of TPB on PTFE surface was verified. The results showed that TPB realized the function of wavelength conversion, but because of the effect of conversion efficiency. The peak counting was reduced. The scintillation signals of three kinds of pure argon were compared. The purity was 99.9999% and 99.9999 9, respectively. The results showed that the purity of argon was higher than that of argon. The larger the yield of scintillation light is, the more the twinkling signal waveform is fitted by using the double component function and the three component function, and the fast component attenuation time is 11.75-15.62ns in the case of double component function. The attenuation time of slow component is 239.34-973.54ns, the ratio of fast and slow component is 0.30-0.11; In the case of three-component function, the fast component decay time is 10.09-10.92 ns, and the slow component attenuation time is 564.72-1852.27ns. The attenuation time of "intermediate component" is 75.37-95.09ns and the ratio of fast and slow component is 0.22-0.07.The attenuation time of slow component increases with the increase of argon purity. Because of the feasibility of monitoring the purity of liquid argon, the scintillation light signal of 99.999% pure liquid argon was obtained. Under the condition of two-component function fitting, the fast component decay time was 19.33ns. The attenuation time of slow component is 211.40 ns and the ratio of fast and slow component is 0.26. The problem of fire damage of photomultiplier tube base plate caused by Paxing law of argon gas is solved. It provides experience for CDEX experiment.
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：P145.9

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