Study of lead-lead collisions at 160 GeV per nucleon

每个核子 160 GeV 的铅-铅碰撞研究

• 批准号: 06402007
• 负责人: SUMI Yoshio
• 金额: $ 16.26万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (A)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06402007/
• 关键词: High-energy heavyion collisions; Multiparticle production; Quark-gluon plasma; Two-particle interferometry (HBT effect); CERN SPS acceleraor; NA44 collaboration; Focussing spectrometer; 高エネルギー・重イオン衝突; HBT効果; CERN-NA44実験; 核子あたり160GeV鉛ビーム

1.We have carried out high-energy heavy-ion experiment NA44 at the CERN SPS.The experimental data on lead-lead collisions at 160 GeV per nucleon as well as those on sulphur-lead collisions at 200 GeV per nucleon have been analyzed.2.From single particle spectra, the temperature of the hadron source created in these collisions is found to depend on the hadron mass. However, our analysis shows that this mass dependence is due to hydrodynamical expansion of the source and the true temperature is independent of hadron species.3.From two-particle interferometry (HBT effect) , we have obtained source size parameters (HBT radii) in three-dimensional analysis. Any measured HBT radii are proportional to the inverse of the square-root of transverse mass m_T.4.This dependence is consistent with the predictions of hydrodynamical model and seems to show the existence of trnasverse flow. The apparent difference of the source size between pions and kaons is ascribed to the difference between the average values of their m_T.5.From transverse HBT radii, for the first time in the world, we have been able to determine the width of freeze-out time distribution for sulphur+ lead collisions to be 2 to 3.5 fm/c, which seems substantially smaller than that expected from QGP phase transition.6.The HBT radii are proportional to the cube-root of the multiplicity density, thereby suggesting that the pion freeze-out takes place under the condition that particle density of the source goes down to a certain constant value.

1.我们在CERN SPS进行了高能重离子实验NA 44，分析了160 GeV/核子的铅-铅碰撞和200 GeV/核子的硫-铅碰撞的实验数据。2.从单粒子谱出发，发现这些碰撞中产生的强子源的温度与强子质量有关。然而，我们的分析表明，这种质量依赖性是由于源的流体动力学膨胀引起的，真实温度与强子种类无关。3.从双粒子干涉（HBT效应）出发，我们得到了三维分析中的源尺寸参数（HBT半径）。实验测得的HBT半径与横向质量m_T平方根的倒数成正比。4.这种关系与流体力学模型的预测一致，似乎表明存在横向流动。π介子和K介子源尺寸的明显差异归因于它们的m_T平均值的差异。5.从横向HBT半径出发，我们在世界上首次确定了硫+铅碰撞的冻结时间分布宽度为2 ~ 3.5fm/c，这似乎比QGP相变所预期的要小得多。6. HBT半径与多重数密度的立方根成正比，由此表明，在源的粒子密度下降到某个恒定值的条件下，发生π介子冻结。

项目成果

H. Boggild: "Coulomb effect in sigle particle distributions" Physics Letters. (in press). (1996)

H. Boggild：“单粒子分布中的库仑效应”物理快报。

B.V.Jacak et al.: "Recent results from NA44 and a review of HBT" Nucl.Phys.A590. 215c-232c (1995)

B.V.Jacak 等人：“NA44 的最新结果和 HBT 的回顾”Nucl.Phys.A590。

H.Beker et al.: "m_T dependence of boson interferometry in heavy-ion collisions at the CERN SPS" Physical Review Letters. (in press). (1995)

H.Beker 等人：“CERN SPS 重离子碰撞中玻色子干涉测量的 m_T 依赖性”物理评论快报。

H.Boggild et al.: "Directional dependence of the pion source in high-energy heavy-ion collisions" Phys. Lett.B349. 386-392 (1995)

H.Boggild 等人：“高能重离子碰撞中π介子源的方向依赖性”Phys。

J.Simon-Gillo et al.: "Deuteron and anti-deuteron production in CERN experiment NA44" Nucl.Phys.A590. 483c-486c (1995)

J.Simon-Gillo 等人：“CERN 实验 NA44 中的氘核和反氘核生产”Nucl.Phys.A590。