نسبت چگالی ترازها با پاریته مخالف در هسته 74Ge با لحاظ گذار فاز نرم حول دمای بحرانی

نوع مقاله : مقاله پژوهشی کامل

نویسندگان

1 گروه فیزیک، دانشگاه پیام نور، تهران، ایران

2 گروه فیزیک، دانشکده علوم پایه، دانشگاه جامع امام حسین (ع)، تهران، ایران

3 موسسه مشترک تحقیقات هسته‌ای، دوبنا، روسیه

چکیده

در این پژوهش نسبت چگالی تراز های هسته‌ ای با پاریته تراز حالت پایه به چگالی تراز های هسته‌ ای با پاریته مخالف برای هسته 74Ge با استفاده از نظریه ابر رسانایی تعمیم‌ یافته در سیستم‌ های بس‌ ذره‌ای با لحاظ گذار فاز نرم حول دمای بحرانی بررسی شده است. نسبت چگالی تراز ها با در نظر گرفتن پارامتر گاف تعمیم‌ یافته به‌ صورت تابعی هموار با افزایش انرژی به سمت یک میل می‌کند . گذار فاز در ناحیه T ≈ 1.1 MeV رخ داده و در ناحیه بالاتر می‌ توان از تقریب توزیع پاریته‌ های یکسان استفاده نمود .

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Ratio of level densities with opposite parities in 74Ge with considering the soft phase transition around critical temperature

نویسندگان [English]

  • O. Nouri 1
  • R. Razavi 2
  • Aazam Rahmatinejad 3
  • Saeed Mohammadi 1
1 Department of Physics, Payame Noor University, Tehran, Iran
2 Physics Department, Faculty of Science, Imam Hossein Comprehensive University, Tehran, Iran
3 Joint Institute for Nuclear Research, Dubna, Russia
چکیده [English]

Ratio of level densities with opposite parities in 74Ge with considering the soft phase transition around critical temperature
In this study , the ratio of nuclear level densities with opposite parities was studied for 74Ge using the generalized, superfluid theory in many - body systems with considering a soft phase transition around the critical temperature. With modified gap parameter, the ratio of nuclear level densities in the form of a smooth function tends to unity with increasing energy . Phase transition occurs at T ≈ 1.1 MeV and at higher energies the approximation of equal parity distribution is applicable .

کلیدواژه‌ها [English]

  • Parity
  • Nuclear level density (NLD)
  • BCS Model
[1] R. Razavi, A. Rahmatinejad, T. Kakavand, F. Taheri, M. Aghajani, A. Khooy, Studying Nuclear Level Densities of 238U in the Nuclear Reactions within the Macroscopic Nuclear Models, Zeitschrift für Naturforschung A 71 2 (2016) 157-160.
[2] R. Razavi, A. Rahmatinejad, T. Kakavand, A. Khooy, Pairing phase transition of nucleons in 89Y and 208Pb, journal of research on many body systems 7 1300435 (2017) 79-85.
[3] S. Rasouli, A.N. Behkami, R. Razavi, A.A. Sabouri Dodaran, M.R. Bayati, Investigation on Neutron-Induced Fission Fragment Angular Distribution of 232Th and 238U, Zeitschrift für Naturforschung A 73 11 (2018) 1075-1081.
[4] A.J. Koning, S. Hilaire, S. Goriely, Global and local level density models, Nuclear Physics A 810 1-4 (2008) 13-76.
[5] H.A. Bethe, An Attempt to Calculate the Number of Energy Levels of a Heavy Nucleus, Physical Review 50 4 (1936) 332.
[6] L.G. Moretto, Thermodynamical properties of a paired nucleus with a fixed number of quasi-particles. Nuclear Physics A 243 1 (1975) 77-99.
[7] R. Razavi, A. Rashed Mohassel, A. Rahmatinejad, A. jabarpour, Systematic of critical temperature of nuclear pairing transition, Nuclear Physics A. 976 61 (2018) 61-69.
[8] A. Rahmatinejad, R. Razavi,T. Kakavand, Thermal quantities of 46Ti, Nuclear Physics A 939 46 (2015) 46-52.
[9] R. Razavi, A.N. Behkami, S. Mohammadi, Microscopic study of nuclear level densities and thermodynamical properties in 170,171,172 Yb, Physica Scripta, 86 4 (2012) 045201.
[10] R. Razavi, Role of neutrons and protons in entropy, spin cut off parameters, and moments of inertia, Physical Review C 88 (2013) 014316.
[11] R. Razavi, T. Kakavand, Level studies of 93Mo via 93Nb (p, nγ) 93Mo reaction and density of discrete levels in 93Mo, Nuclear Technology and Radiation Protection 26 1 (2012) 69-73.
[12] N. Cerf, Parity Dependence of the Nuclear Level Density, Nuclear Physics A 554 (1993) 85-106.
[13] B.V. Rao, H.M. Agrawal, Parity Dependence of the Nuclear Level Density at High Excitation, Nuclear Physics A 592 (1995) 1-8.
[14] A. Rahmatinejad, R. Razavi, T. Kakavand, Role of neutron and proton system in spin cut off parameter and entropy of 89, 90Y, Nuclear Physics A Vol 941 (2015) 145-151.
[15] J. Bardeen, L.N. Cooper, J.R. Schrieffer, Theory of superconductivity, Physical Review 108 (1957) 1175.
[16] R. Razavi, et al., Ratio of neutron and proton entropy excess in 121Sn compared to 122Sn, Physical Review C 86 (2012) 047303.
[17] D. Mocelj et al., Parity-Dependence in the Nuclear Level Density, Nuclear Physics A 758 (2005) 154c–157c.
[18] A.N. Behkami, J.R. Huizenga, Comparison Of Experimental Level Densities and Spin Cut Off factors with Microscopic Theory For Nuclei Near A= 60, Nuclear Physics A 217 (1973) 78-92.
[19] A. Rahmatinejad, R. Razavi, T. Kakavand, Temperature dependent pairing gap in nucle, International Journal of Modern Physics E 27 01 (2018) 1850003.
[20] D. Mocelj et al., Large-scale prediction of the parity distribution in the nuclear level density and application to astrophysical reaction rates, Phys. Rev. C 75 (2007) 045805.
[21] Y. Alhassid, G.F. Bertsch, S. Liu and H. Nakada, Parity Dependence of Nuclear Level Densities, Physical Review Letter 84 19 (2000) 4313- 4316.
[22] A. Rahmatinejad, R. Razavi and T. Kakavand, Studying temperature dependence of pairing gap parameter in a nucleus as a small superconducting system, International Journal of Modern Physics E 25 (2016) 1650050.
[23] T. Renstrom, et al., Low-energy enhancement in the γ-ray strength functions of 73,74Ge, Physical Review C 93 (2016) 064302.
[24] R. Razavi, O. Nouri, A. Rahmatinejad, S. Mohammadi, Parity equilibration in nuclear level densities of 159–166Dy, Modern Physics Letters A 35. 38 (2020) 2050315.