本文選題：RHIC + 能區(qū)��； 參考：《中國(guó)科學(xué)技術(shù)大學(xué)》2016年博士論文

【摘要】：量子色動(dòng)力學(xué)是用來(lái)描述夸克和膠子間強(qiáng)相互作用的規(guī)范場(chǎng)理論。格點(diǎn)量子色動(dòng)力學(xué)預(yù)言在高溫或高重子化學(xué)勢(shì)的條件下會(huì)發(fā)生從強(qiáng)子物質(zhì)到夸克膠子等離子體(QGP)的相變。坐落在美國(guó)布魯克海文國(guó)家實(shí)驗(yàn)室(BNL)的相對(duì)論重離子對(duì)撞機(jī)(RHIC)是專門(mén)用于研究夸克膠子等離子體性質(zhì)以及量子色動(dòng)力學(xué)相圖的實(shí)驗(yàn)裝置。雙輕子不參與強(qiáng)相互作用,并且可以在重離子對(duì)撞整個(gè)演化過(guò)程中產(chǎn)生,因此,雙輕子的測(cè)量在研究這種高溫高密物質(zhì)中起著至關(guān)重要的作用。根據(jù)不同的產(chǎn)生機(jī)制,雙輕子的不變質(zhì)量譜一般被劃分成三個(gè)質(zhì)量區(qū)間。高質(zhì)量區(qū)間(HMR, Mll MJ/ψ),雙輕子主要由初始的硬過(guò)程產(chǎn)生,例如Drell-Yan,夸克偶素的衰變。中間質(zhì)量區(qū)間(IMR, MφMllMJ/ψ),雙輕子主要由夸克膠子等離子體的熱輻射以及開(kāi)粲的半輕子衰變產(chǎn)生,其中熱輻射的雙輕子產(chǎn)額可用于測(cè)量夸克膠子等離子體的溫度。低質(zhì)量區(qū)間(LMR, MuMφ),雙輕子主要由在強(qiáng)子介質(zhì)中矢量介子(ρ,ω,φ,等)的衰變產(chǎn)生,他們可用于研究介質(zhì)中的手征對(duì)稱性恢復(fù)。此外,ALICE合作組最近觀察到在質(zhì)心能量為2.76 TeV的鉛核-鉛核偏心對(duì)撞中,超低橫動(dòng)量(pT0.3 GeV/c)的前向快度J/(?)產(chǎn)額有非常大的增強(qiáng)。這部分增強(qiáng)有可能來(lái)自相干光產(chǎn)生過(guò)程。如果在偏心重離子對(duì)撞中,也可以通過(guò)相干光產(chǎn)生生成ρ介子,這部分ρ介子可用作一個(gè)直接測(cè)量夸克膠子等離子體性質(zhì)的探針。本論文利用位于相對(duì)論重離子對(duì)撞機(jī)上的螺旋徑跡探測(cè)器(STAR),首次研究了雙輕子在鈾核-鈾核對(duì)撞中的產(chǎn)生。用于該分析研究的數(shù)據(jù)采集于2012年。利用時(shí)間投影室測(cè)量的電離能損以及飛行時(shí)間探測(cè)器測(cè)量的粒子速度進(jìn)行正負(fù)電子的鑒別。在鈾核-鈾核的最小無(wú)偏對(duì)撞中(中心度：0-80%),鑒別出來(lái)的電子整體純度可以達(dá)到95%。通過(guò)對(duì)比在最小無(wú)偏對(duì)撞中測(cè)量的STAR接收度內(nèi)(pTe 0.2 GeV/c, |ηe|1, and |yee|1)的雙輕子不變質(zhì)量譜和不包含ρ介子貢獻(xiàn)的強(qiáng)子衰變模擬(cocktail),我們發(fā)現(xiàn)在類ρ質(zhì)量區(qū)間0.3-0.76 GeV/c2內(nèi),測(cè)量的雙輕子產(chǎn)額比模擬的產(chǎn)額高2.1±0.1(stat.)±0.2(sys.)±0.3(cocktail)倍。我們還系統(tǒng)的測(cè)量了不同橫動(dòng)量以及中心度區(qū)間的雙輕子不變質(zhì)量譜,發(fā)現(xiàn)此增強(qiáng)因子并沒(méi)有很強(qiáng)的中心度以及橫動(dòng)量依賴性。為了定量的研究這些雙輕子增強(qiáng),我們還測(cè)量了修正STAR接收度的雙輕子增強(qiáng)譜(data-cocktail ).上面提到的所有雙輕子增強(qiáng)譜都可以用一個(gè)包含ρ展寬的譜函數(shù)以及夸克膠子等離子體熱輻射貢獻(xiàn)的理論模型描述。ρ介子譜在高溫高密介質(zhì)中的展寬被認(rèn)為和手征對(duì)稱性恢復(fù)有關(guān)。進(jìn)一步的分析研究表明,帶電粒子密度(dNch/dy)歸一的修正了STAR接收度的積分增強(qiáng)產(chǎn)額(積分區(qū)間：0.4Mee0.75 GeV/c2)有很強(qiáng)的中心度以及對(duì)撞能量的依賴性。中心對(duì)撞中的歸一積分增強(qiáng)產(chǎn)額比偏心對(duì)撞以及低能量對(duì)撞的產(chǎn)額要高。最近一個(gè)理論模型指出,在質(zhì)心能量為6到200 GeV區(qū)間內(nèi),dNch/dy歸一的積分增強(qiáng)產(chǎn)額正比于重離子對(duì)撞中產(chǎn)生介質(zhì)的壽命。這預(yù)示著在鈾核-鈾核中心對(duì)撞中產(chǎn)生的介質(zhì)的壽命比在偏心對(duì)撞中或者低質(zhì)心能量重離子對(duì)撞中產(chǎn)生的介質(zhì)壽命長(zhǎng)。本論文還首次測(cè)量了鈾核-鈾核對(duì)撞中STAR接收度內(nèi)超低橫動(dòng)量(Pr 0.15 GeV/c)的雙輕子不變質(zhì)量譜。相對(duì)于強(qiáng)子衰變的模擬產(chǎn)額,偏心對(duì)撞中的雙輕子產(chǎn)額在整個(gè)質(zhì)量區(qū)間都有很大的增強(qiáng)。在質(zhì)量區(qū)間0.4-0.76 GeV/c2和2.8-3.2 GeV/c2中,增強(qiáng)因子分別為16.4±1.1(stat.) ±2.6(sys.)± 4.2(cocktail), 20.4±4.2(star.)±3.0(sys.)±3.2(cocktail)。這些增強(qiáng)可能來(lái)自于相干光產(chǎn)生過(guò)程。我們還測(cè)量了鈾核-鈾核對(duì)撞中STAR接收度內(nèi)不同質(zhì)量區(qū)間的雙輕子橫動(dòng)量譜(0.4Meκε 0.76 GeV/c2, 1.2 Meε2.67GeV/c2, and 2.8 Meε 3.2 GeV/c2),發(fā)現(xiàn)這些橫動(dòng)量譜的形狀在偏心對(duì)撞中在0.1 GeV/c附近發(fā)生急劇變化。此外,本論文還報(bào)告了兩種氣體探測(cè)器-迷你漂移厚氣體電子倍增室(mini-drift THGEM )和多氣隙阻性板室(MRPC)的研制以及測(cè)試結(jié)果。THGEM用作穿越輻射探測(cè)器(TRD)的讀出探測(cè)器,用來(lái)鑒別電子離子對(duì)撞機(jī)上的前向散射電子和提供額外的電離能損(dE/dx )測(cè)量,后者對(duì)小角度散射的帶電粒子徑跡重建非常重要。這是首次提出用THGEM作為T(mén)RD的讀出探測(cè)器。宇宙線測(cè)試結(jié)果表明，，在工作電壓下,THGEM的探測(cè)效率高于94%,位置分辨能達(dá)到220μm。由于THGEM具有非常好的位置分辨以及相對(duì)厚的電離區(qū),THGEM展現(xiàn)出非常卓越的徑跡重建能力。最后,測(cè)試結(jié)果表明THGEM增益均勻性以及穩(wěn)定性也非常好。為了提高北京譜儀的粒子鑒別能力,MRPC被用來(lái)升級(jí)北京譜儀端蓋飛行時(shí)間探測(cè)器(eTOF)。我們?cè)谡?fù)電子對(duì)撞機(jī)E3束流線上用動(dòng)量為600MeV/c的質(zhì)子束測(cè)試了單端讀出和雙端讀出MRPC、~在工作高壓下,兩種MRPC的探測(cè)效率都高于98%。單端讀出MRPC的時(shí)間分辨為47 ps,但有帶電粒子入射位置的依賴性。雙端讀出MRPC的時(shí)間分辨為40 ps,且沒(méi)有帶電粒子入射位置的依賴性。根據(jù)這次束流測(cè)試結(jié)果,雙端讀出MRPC被用于北京譜儀的eTOF升級(jí)。北京譜儀的eTOF升級(jí)已于2015年11月完成,對(duì)電子的時(shí)間分辨可達(dá)到60 ps,遠(yuǎn)好于其設(shè)計(jì)指標(biāo)(80 ps)。
[Abstract]:Quantum chrodynamics is a standard field theory used to describe the strong interaction between quarks and gluons. Lattice quantum chromo dynamics predicts that the phase transition from hadron matter to quark gluon plasma (QGP) occurs under the condition of high temperature or high baryon chemical potential. The relativistic heavy ion pair located in the Brook National Laboratory (BNL) of the United States The Collider (RHIC) is an experimental device specially used to study the properties of the quark gluon plasma and the quantum chromatic phase diagram. The double lepton does not participate in the strong interaction and can be produced during the entire evolution of heavy ion collisions. Therefore, the measurement of the double lepton plays a vital role in the study of the high temperature and high density material. In the same generation mechanism, the invariant mass spectra of the dual leptons are generally divided into three mass intervals. The HMR, Mll MJ/ are mainly produced by the initial hard processes, such as the decay of Drell-Yan, quarkeven, the intermediate mass interval (IMR, M phi MllMJ/), and the dual leptons mainly by the heat radiation of the quark gluon plasma and the charm of the quark plasma. Semi lepton decay in which the double lepton yield of heat radiation can be used to measure the temperature of the quark gluon plasma. The low mass interval (LMR, MuM phi), the two leptons are mainly produced by the decay of the vector mesons (rho, Omega, phi, etc.) in the hadronic medium, and they can be used in the chiral symmetry recovery in the study medium. In addition, the ALICE cooperation group recently looked at it. It is observed that in the eccentricity of the lead core eccentricity of the centroid energy of 2.76 TeV, the forward fast J/ (?) output of the ultra low transverse momentum (pT0.3 GeV/c) is greatly enhanced. This part of the enhancement may come from the coherent light production process. If in the eccentrically heavy ion collisions, the P meson can also be generated by the coherent light. This part of the P meson can be used as a meson. A probe to directly measure the properties of the quark gluon plasma. This paper first studied the production of double leptons in uranium nuclear uranium nuclear collisions by using the spiral track detector (STAR) on the Relativistic Heavy Ion Collider. The data used in this analysis were collected in 2012. The ionization energy loss and flight measured by the time projection chamber. The particle velocity measured by the row time detector is identified by the positive and negative electrons. In the minimum unbiased collision (center degree: 0-80%) in the uranium nuclear uranium core (center degree: 0-80%), the identified electronic purity can reach the two lepton invariant mass spectra (pTe 0.2 GeV/c, pTe e|1, and |yee|1) measured by the contrast in the minimum unbiased collision. And the hadron decay simulation (cocktail), which does not contain the contribution of the P meson (cocktail), we find that the measured double lepton yield is 2.1 + 0.1 (stat.) + 0.2 (sys.) + 0.3 (cocktail) times higher than the analog output in the class Rho mass interval (stat.). We also systematically measured the two lepton invariant mass spectra of different transverse momentum and central degree, and found this The enhancement factor does not have a strong centrality and transverse momentum dependence. In order to quantify these dual lepton enhancements, we also measured the double lepton enhancement spectrum (data-cocktail) for the correction of the STAR reception. All of the two lepton enhancement spectra mentioned above can be used by a spectral function containing Rho and the heat of the quark gluon plasma. The theoretical model of the radiation contribution is described. The broadening of the P meson spectrum in high temperature and high density media is considered to be related to the chiral symmetry recovery. Further analysis shows that the integral enhancement of the charged particle density (dNch/dy) is corrected by the integral enhancement of the STAR receiver (integral interval: 0.4Mee0.75 GeV/c2) with a strong centrality and collision energy. The last theoretical model indicates that the integral enhancement of the dNch/dy return is proportional to the lifetime of the medium in the heavy ion collisions, which indicates that in the uranium nuclear uranium nuclear center, the latest theoretical model points out that in the center of mass energy is 6 to 200 GeV intervals. The lifetime of the medium produced in the collision is longer than that produced in the eccentrically collided or low centroid energy heavy ion collisions. This paper also first measured the two lepton invariant mass spectra of the ultra low transverse momentum (Pr 0.15 GeV/c) in the STAR receiving degree of uranium nuclear and uranium nuclear pair collisions. The yield of lepton is greatly enhanced in the whole mass range. In the mass interval 0.4-0.76 GeV/c2 and 2.8-3.2 GeV/c2, the enhancement factors are 16.4 + 1.1 (stat.) + 2.6 (sys.) + 4.2 (cocktail), 20.4 + 4.2 (star.) + 3 (sys.) + 3.2 (cocktail). These enhancements may come from the coherent light production process. We also measured uranium nuclear uranium nucleation The two lepton transverse momentum spectra (0.4Me kappa e 0.76 GeV/c2, 1.2 Me e 2.67GeV/c2, and 2.8 Me e 3.2 GeV/c2) in the different mass intervals in the STAR receiving degree are found. It is found that the shape of these transverse momentum spectra changes sharply near 0.1 GeV/c in the eccentricity collision. In addition, this paper also reported two gas detectors - Mini drift thick gas electrons. The development and test results of the multiplier chamber (mini-drift THGEM) and multi air gap resistive plate chamber (MRPC),.THGEM is used as a read-out detector to cross the radiation detector (TRD) to identify the forward scattering electrons on an electron ion collider and provide an additional ionization energy loss (dE/dx) measurement. The latter reconstructs charged particle tracks for small angle scattering. It is often important. This is the first time to propose a readout detector using THGEM as a TRD. The results of the cosmic ray test show that the detection efficiency of THGEM is higher than 94% under the operating voltage and the position resolution can reach 220 M. because THGEM has a very good position resolution and a relatively thick ionization area, and the THGEM shows excellent track reconstruction ability. Finally, the test is tested. The results show that the THGEM gain uniformity and stability are very good. In order to improve the particle identification ability of the Beijing spectrometer, MRPC is used to upgrade the end cover flight time detector (eTOF) of the Beijing spectrometer. We test the single end readout and double end readout MRPC with the proton beam of 600MeV/c on the E3 beam line of the positive and negative electron collider. Under high pressure, the detection efficiency of the two kinds of MRPC is higher than the time resolution of the 98%. single end readout MRPC is 47 PS, but it has the dependence on the incident position of charged particles. The time resolution of the dual end readout MRPC is 40 PS, and there is no dependence on the incident position of the charged particles. According to the results of the beam test, the dual end readout MRPC is used for the eTOF upgrade of the Beijing spectrometer. The eTOF upgrade of the Beijing spectrometer has been completed in November 2015. The time resolution of the electron can reach 60 PS, much better than its design index (80 PS).
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：O572.33


本文編號(hào)：2004414