核能與可再生能源外文翻譯--中能區(qū)橢圓流和轉(zhuǎn)變能的系統(tǒng)質(zhì)量依賴

1、<p><b>　　中文2200字</b></p><p>　　畢業(yè)設(shè)計(jì)(論文)外文資料翻譯</p><p>　　系 ： 核能與可再生能源 </p><p>　　專 業(yè)： 核工程與核技術(shù) 091 </p><p>　　姓 名：

2、 </p><p>　　學(xué) 號(hào)： </p><p>　　外文出處： PHYSICAL REVIEW C 74 </p><p>　　014602(2006) </p><p>　　附 件： 1

3、.外文資料翻譯譯文；2.外文原文。 </p><p>　　附件1：外文資料翻譯譯文</p><p>　　中能區(qū)橢圓流和轉(zhuǎn)變能的系統(tǒng)質(zhì)量依賴</p><p><b>　　張英遜 李祝霞</b></p><p>　　1中國(guó)原子能科學(xué)研究院能源、郵政信箱275(18)、北京102413,中華人民共和國(guó)</p&g

4、t;<p>　　2中心理論核物理、國(guó)家實(shí)驗(yàn)室的蘭州重離子加速器,蘭州730000,中華人民共和國(guó)</p><p>　　3理論物理研究所,中國(guó)學(xué)術(shù)的科學(xué),北京100080,中華人民共和國(guó)</p><p>　　(收錄于2005年12月12日,2006年7月7日出版)</p><p>　　橢圓流Z ≤2粒子在重離子碰撞的能量從數(shù)十到數(shù)百兆電子伏特每核子研究通

5、過(guò)傳輸模型。一個(gè)新版本的改進(jìn)的量子分子動(dòng)力學(xué)模型(ImQMD05)。該模型采用了一個(gè)完整的 Skyrme 勢(shì)能密度泛函數(shù)。不同的等效相互作用的影響和介質(zhì)修正的核子核子橫截面的橢圓流進(jìn)行了研究。我們的結(jié)果表明,軟核狀態(tài)方程和入射能量依賴于介質(zhì)核子核子橫截面用于描述激發(fā)態(tài)的中能橢圓流函數(shù)。橢圓流躍遷能的大小對(duì)中能的依賴關(guān)系也進(jìn)行了探討。系統(tǒng)質(zhì)量依賴躍遷能與系統(tǒng)質(zhì)量相符合，指數(shù)為0.223。</p><p>　　中能重

6、離子碰撞(HICs)研究領(lǐng)域的一個(gè)主要目標(biāo)是提取更準(zhǔn)確信息的核狀態(tài)方程(EoS)。最近，已經(jīng)從重離子反應(yīng)數(shù)據(jù)中對(duì)確定核物質(zhì)狀態(tài)方程取得重大進(jìn)展。集體流在有效的觀測(cè)量中扮演了一個(gè)突出的角色。大量的理論和實(shí)驗(yàn)工作耗費(fèi)在了中能重離子碰撞中集體流的研究上面。橢圓流已被證明是一個(gè)推倒?fàn)顟B(tài)方程和重離子碰撞力學(xué)多產(chǎn)的課題。</p><p>　　最近,激發(fā)函數(shù)橢圓流參數(shù)的能量從費(fèi)米能級(jí)到相對(duì)論能量的 197 Au + 197 A

7、u 式中已經(jīng)通過(guò) FOPI, INDRA, 和 ALADIN 協(xié)作的測(cè)量,躍遷能從正到負(fù)的橢圓流被確認(rèn),它大約在 100MeV/u。平均場(chǎng)和兩體碰撞在這個(gè)能區(qū)中都扮著重要的角色。在低能區(qū)平均場(chǎng)起關(guān)鍵性作用,然后隨著能量的增加，兩體碰撞逐漸成為主導(dǎo)。因此, 在這個(gè)能區(qū)，隨著對(duì)橢圓流激勵(lì)函數(shù)的深入研究，可以對(duì)與核子核子等效相互作用的核物質(zhì)狀態(tài)方程和介質(zhì)修正核子核子橫截面相關(guān)方面提供更多有用的信息。在中能區(qū)，橢圓流的躍遷能可能對(duì)提取核反應(yīng)信

8、息特別有用。當(dāng)能量高于躍遷能，橢圓流將有益于提取試驗(yàn)核子核子碰撞截面，因?yàn)閮审w碰撞在這個(gè)能區(qū)對(duì)集體流發(fā)揮更重要的作用。這項(xiàng)工作的另一個(gè)目的是通過(guò)橢圓流流入重離子碰撞中能量從費(fèi)米能量到相對(duì)論能量的過(guò)程，來(lái)探討試驗(yàn)核子核子橫截面。</p><p>　　在這篇報(bào)告中,我們應(yīng)用最新版本改進(jìn)的量子分子動(dòng)力學(xué)模型(ImQMD05) 對(duì)中能 197 Au + 197Au 核反應(yīng)，來(lái)研究激發(fā)函數(shù)橢圓流參數(shù)，并通過(guò)比較測(cè)量和模型計(jì)

9、算來(lái)提取等效相互作用中核狀態(tài)方程和介質(zhì)修正核子核子橫截面的信息。系統(tǒng)質(zhì)量依賴的橢圓流中的躍遷能，也將對(duì) 58Ni+ 58Ni 和 197 Au + 197Au 進(jìn)行研究。</p><p>　　為方便讀者,我們首先給出一個(gè)簡(jiǎn)要介紹 ImQMD05 的模型。ImQMD 模型的主要改進(jìn)對(duì)比與普通的IQMD模型來(lái)源于于 (1)同位旋相關(guān)作用和依賴的表面能量在能量密度方面功能, (2)單粒子占有數(shù)的限制, (3)系統(tǒng)質(zhì)量依

10、賴的波包寬度。這個(gè)ImQMD模型能完美地描述在中能重離子碰撞中的離子簇的產(chǎn)生量。在 ImQMD05 模型中,我們介紹了完整的 Skyrme 勢(shì)能密度泛函，除了局部相互作用的自旋軌道,它允許我們選擇各種 Skyrme 參數(shù)，來(lái)描述基態(tài)的核子和飽和核物質(zhì)，類似但不同性質(zhì)的飽和密度。</p><p>　　構(gòu)造的片段通過(guò)結(jié)合模型廣泛應(yīng)用于 QMD 模型的計(jì)算中,相對(duì)動(dòng)量小于P0和相對(duì)距離小于R0的離子結(jié)合成一個(gè)離子簇(在

11、這里,取 R0 = 3.0fm P0 = 250MeV/ c)。這里分別顯示了在 Ebeam = 60、150、400MeV/u 的對(duì)心碰撞中，197 Au + 197Au 的電荷分布的片段。從中可以看到,計(jì)算結(jié)果對(duì)電荷分布的片段與實(shí)測(cè)數(shù)據(jù)吻合較好。然后,我們應(yīng)用 ImQMD05 模型來(lái)研究橢圓流參數(shù)的激勵(lì)函數(shù)和試著提取有效相互作用和試驗(yàn)的兩體橫截面的有效信息。</p><p>　　隨著能量進(jìn)一步增大, v2變

12、成負(fù)值，當(dāng) SkP 和 SkM? 大約等于 400MeV/u 和SLy7 和 SIII 大約等于 250MeV/u 時(shí),它達(dá)到最大負(fù)值。用 SIII 和 SLy7 比 SkP 和 SkM? 的計(jì)算在壓縮區(qū)提供更強(qiáng)的壓力,這使得 SLy7 和 SIII 計(jì)算橢圓流時(shí)在較低能量達(dá)到最大了負(fù)值v2。在比較了用四種 Skyrme 參數(shù)測(cè)量的預(yù)測(cè)結(jié)果后，,我們發(fā)現(xiàn)用 SkP 和 SkM? 計(jì)算的結(jié)果，與實(shí)驗(yàn)數(shù)據(jù)幾乎一致。在達(dá)到最大負(fù)值橢圓流后,v

13、2值再次減少。這意味著在v2達(dá)到最大負(fù)值后旁流的速度更快了。觀測(cè)了從90MeV/u到1.93 GeV /u的核阻止后，我們觀察到 197 Au + 197 Au 的最大核阻止大約在400MeV/u。我們看到橢圓流參數(shù)達(dá)到最大負(fù)值的能量的與達(dá)到最大核阻止的能量一致。很明顯,如果反應(yīng)體系在某一能量時(shí)達(dá)到最大核阻止, 在反應(yīng)中的物質(zhì)形成將會(huì)達(dá)到最小的透明度,因此大多數(shù)粒子優(yōu)先發(fā)射出平面。</p><p>　　現(xiàn)在,讓我

14、們探討試驗(yàn)橢圓流的核子核子橫截面的影響。這里顯示了當(dāng) η= 0.2,0.0,﹣0.4 時(shí)橢圓流激發(fā)函數(shù)的參數(shù)的計(jì)算,我們有效地研究了在不同核能環(huán)境下試驗(yàn)核子核子橫截面以及散射對(duì)的相對(duì)動(dòng)量。SkP Skyrme 參數(shù)在計(jì)算中被采用。我們看到,在能量低于躍遷能時(shí), 當(dāng)η= 0.2 和η= 0.0 時(shí)，無(wú)論給實(shí)驗(yàn)數(shù)據(jù)合理的解釋，還是當(dāng)轟擊能量高于躍遷能時(shí)差別增大，計(jì)算結(jié)果之間的差異都很小。隨著能量進(jìn)一步增大, 當(dāng)η= 0.2 時(shí)，負(fù)橢圓流計(jì)算

15、結(jié)果太弱(即,負(fù)橢圓流參數(shù)太小)。它需要一個(gè)較小的η甚至是負(fù)η。根據(jù)實(shí)驗(yàn)結(jié)果，當(dāng)η約為?0.4，入射能大約為400MeV/u時(shí)，我們?yōu)檫@個(gè)例子找到一個(gè)合理的解釋;即,在入射能約為400MeV/u時(shí),中能兩體截面的提取大于自由截面。據(jù)預(yù)測(cè), 根據(jù)兩個(gè)碰撞的核子的相對(duì)動(dòng)量，在超常密度中的中能彈性核子核子截面的行為先抑制,然后增強(qiáng)。還預(yù)言了,中能彈性核子核子截面隨溫度上升而增加。如果我們僅僅考慮核子對(duì)碰撞的相對(duì)動(dòng)量大約等于彈射體和靶子的相對(duì)動(dòng)

16、量,假設(shè)溫度明顯從幾十增加到幾百M(fèi)eV/u, 那么，橢圓流中，從中能核子核子橫截面提取的信息和預(yù)測(cè)定性一致。本</p><p>　　我們注意到,計(jì)算結(jié)果不完全與在整個(gè)能區(qū)測(cè)量一致。這意味著一個(gè)更有條理的處理方法，包括在中等截面和平均場(chǎng),特別是一個(gè)更有條理更明確動(dòng)量公式的使用是非常有必要的,但這是很難做的。</p><p><b>　　鳴謝</b></p>

17、<p>　　我們感謝 Danielewicz 博士的友情討論。這項(xiàng)工作分別受到了中國(guó)國(guó)家自然科學(xué)基金委員會(huì)和國(guó)家重點(diǎn)基礎(chǔ)研發(fā)規(guī)劃項(xiàng)目的贊助，并編號(hào)為10175093，10235030，10235020，和G20000774。</p><p><b>　　附件2：外文原文</b></p><p>　　Elliptic flow and system size

18、 dependence of transition energies at intermediate energies</p><p>　　Yingxun Zhang Zhuxia Li</p><p>　　1China Institute of Atomic Energy, P.O. Box 275 (18), Beijing 102413, People’s Republic o

19、f China</p><p>　　2Center of Theoretical Nuclear Physics, National Laboratory of Lanzhou Heavy Ion Accelerator, Lanzhou 730000, People’s Republic of China</p><p>　　3Institute of Theoretical Physi

20、cs, Chinese Academic of Science, Beijing 100080, People’s Republic of China</p><p>　　(Received 12 December 2005; published 7 July 2006)</p><p>　　The elliptic flow for Z ≤2 particles in heavy ion

21、 collisions at energies from several tens to several hundreds MeV per nucleon is investigated by means of a transport model, i.e., a new version of the improved quantum molecular dynamics model (ImQMD05). This model empl

22、oys a complete Skyrme potential energy density functional. The influence of different effective interactions and medium corrections of nucleon-nucleon cross sections on the elliptic flow are studied. Our results show tha

23、t a soft nu</p><p>　　A main goal of the research area of heavy ion collisions (HICs) at intermediate energies is to extract more accurate information on the nuclear equation of state (EoS). Considerable prog

24、ress has been made recently in determining the equation of state of nuclear matter from heavy ion reaction data . A prominent role among available observables is played by collective flow. Much theoretical and experiment

25、al effort has been expended on the study of collective flow in HICs . The elliptic flow has pr</p><p>　　Recently, the excitation function of elliptic flow parameters at energies from Fermi energy to the rela

26、tivistic energy regime for 197Au+197Au has been measured by the FOPI, INDRA, and ALADIN Collaborations , and the transition energy from positive to negative elliptic flow was confirmed, which is around 100 MeV/nucleon. B

27、oth the mean field and two-body collision parts play important roles in thisenergy region. The mean field plays a dominant role at low energies, and then gradually the two-body </p><p>　　In this report, we a

28、pply the new version of the improved quantum molecular dynamics model (ImQMD05) to study the excitation function of elliptic flow parameters for 197Au+197Au at intermediate energies, and through the comparison between me

29、asurement and model calculations to extract the information on the effective interaction related to the EoS and the medium correction of nucleon-nucleon cross sections. The system size dependence of transition energies o

30、f elliptic flow from 58Ni+58Ni to 197Au+</p><p>　　For the convenience of the readers, we first give a brief introduction of the ImQMD05 model. The main developments of the ImQMD model compared with the usual

31、 IQMD model are the introduction of (1) the isospin independent and dependent surface energy terms in the energy density functional, (2) the constraint on the single-particle occupation number, and (3) the system size de

32、pendent wave packet width . The ImQMD model can successfully describe the yields of clusters in intermediate energy heavy i</p><p>　　The fragments are constructed by means of the coalescence model widely use

33、d in the QMD model calculations in which particles with relative momenta smaller than P0 and relative distances smaller than R0 are coalesced into one cluster (here, R0 = 3.0 fm and P0 = 250 MeV/c are adopted). It shows

34、the charge distribution of fragments for 197Au+197Au at Ebeam = 60, 150, 400 MeV/nucleon at central collisions, respectively. One sees from it that the calculation results for charge distribution of fragmen</p>&l

35、t;p>　　As energy further increases, v2 becomes negative, and it reaches maximal negative value around 400 MeV/nucleon for SkP and SkM? and 250 for SLy7 and SIII. The calculations with SIII and SLy7 provide stronger pre

36、ssure at the compression zone compared with SkP and SkM?, which makes calculated elliptic flow to reach the maximal negative v2 at lower energy for SIII and SLy7. In comparing the predictions made with the four Skyrme in

37、teractions with measurements, we find that the results with SkP and S</p><p>　　Now, let us investigate the influence of the medium correction of nucleon-nucleon cross sections on elliptic flow. It shows the

38、excitation functions of elliptic flow parameters calculated with η = 0.2, 0.0,?0.4 , by which we effectively study the medium correction of nucleon nucleon cross sections at different nuclear environments as well as the

39、relative momentum of the scattering pair. The SkP Skyrme interaction is adopted in the calculations. We see that at energies lower than transition energ</p><p>　　We notice that the calculation results are no

40、t in full agreement with measurements in the whole energy region. This means that a more self-consistent treatment including the in-medium cross section and the mean field and, especially, a more self-consistent explicit

41、ly momentum dependent term is needed, but this has been difficult to do.</p><p>　　ACKNOWLEDGMENTS</p><p>　　We thank Dr. P. Danielewicz for helpful discussions. This work is supported by the Nati