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高能重离子碰撞中正负荷电粒子比单事例起伏研究 总被引:2,自引:0,他引:2
用强子和弦级联模型,JPCIAE及相应的Monte Carlo事例产生器,研究相对论性核–核碰撞中有限快度区间内正负荷电粒子比单事例起伏与能量、中心度、共振态衰变及快度间隔的关系.JPCIAE模型能够较好地符合CERN/SPS能区Pb+Pb碰撞的实验结果.本文还用此模型预言了RHIC能区Au+Au碰撞和ALICE能区Pb+Pb碰撞中的正负荷电粒子比单事例起伏.可以看出碰撞能量、中心度、共振态衰变及快度间隔对正负荷电粒子比单事例起伏的影响都不大. 相似文献
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D5_c型Y_2C_3的高压合成 总被引:1,自引:0,他引:1
从经验中知道,高超导转变温度Tc的超导体,往往是在B1、D5_c和A15(或Nacl、Pu_2C_3和Cr_3Si)型结构的三种立方晶体材料中找到的.合成和研究这三种材料对探索高Tc超导体是很有意义的.我们曾用高压高温法研究过B1、A15型结构的超导材料,而用高温、高压法去研究Pu_2C_3型的材料有特定的意义.因为Pu_2C_3型(Th_xY_(1-x))_2C_3材料(Tc最高可达17K)是用高压高温法合成出来的.为了研究这种结构并摸索它的成相范围、合成工艺,首先选取二元的Pu_2C_3型结构的Y_2C_3,作为高温高压合成的对象.本文将给出初步结果. 相似文献
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将HI-13北京串列加速器次级束流线产生的放射性核素 7Be分别注入到天然Pt和Al中, 利用两个高纯锗探测器同时测量 7Be 经由7Li第一激发态衰变后跃迁到基态产生的478 keVγ射线产额随时间的变化, 结果在实验误差范围内(<0.14%)没有发现7Be衰变率在Pt与Al中有明显差别, 讨论了这两种材料的电子亲和势及有效电子密度与EC衰变率的关系。 We measured the variation of the decay rate of 7Be implanted in Pt and Al host materials by detecting the 478 keV γ ray emitted from the first excited state of 7Li which is produced by EC decay of 7Be with two HPGe detectors simultaneously, and found no difference of 7Be decay rate in Pt from that in Al within our experimental error (<0.14%). We discussed the relation of the decay rate variation with the electronic affinities and effective electron densities near the implanted ions in the two different host materials. 相似文献
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The shower shape of n, n^-, p, p^-, K^+, π^+ and photons, generated by JPCIAE code for 5.5 TeV/A ^208pb+^208pb collisions, incident on the ALICE photon spectrometer (PHOS), is analyzed with the principal component analysis (PCA) method. The efficiency dependence of purity for the photon discrimination is simulated for the deposited energy ranges 0.5-2 GeV, 2-10 GeV, 10-50 GeV and 50-100 GeV. The result shows that in the energy range of 0.5 to 100 GeV, the efficiency of the photon identification can reach 90% with purity of 90%. 相似文献
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Online The decay rate variation of r Be implanted into platinum and aluminum host materials has been measured via detecting the 478 keV γ-rays from the first excited state of r Li populated in the electron capture decay of7r Be. The result (λpt - λA1)λ0 = (-0.17 ± 0.13)% is obtained. It is smaller than the theoretical estimate from the TB-LMTO calculation (0.38%). This is quite different from our previous study which showed a 1arger decay rate variation ((0.8 ± 0.2)%) than the TB-LMTO calculation (0.30%) of 7 Be in palladium and gold. It is suggested that the effective quasi-free electron density near the implanted ions in different metal host materials may play an important role in r Be EC decay rate variation in addition to the electronic affinity and crystal structure of different host materials. 相似文献