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MINISTRY OF EDUCATION AND TRAINING MINISTRY OF SCIENCE AND TECHNOLOGY Vietnam Atomic Energy Institute ——————— NGUYỄN NGỌC ANH EXPERIMENTAL STUDY ON LEVEL STRUCTURE OF EXCITED 172 Yb AND 153 Sm NUCLEI USING NEUTRON BEAM FROM DALAT NUCLEAR RESEARCH REACTOR DOCTORAL DISSERTATION IN PHYSICS HÀ NỘI - 2018 MINISTRY OF EDUCATION AND TRAINING MINISTRY OF SCIENCE AND TECHNOLOGY Vietnam Atomic Energy Institute ——————— NGUYỄN NGỌC ANH EXPERIMENTAL STUDY ON LEVEL STRUCTURE OF EXCITED 172 Yb AND 153 Sm NUCLEI USING NEUTRON BEAM FROM DALAT NUCLEAR RESEARCH REACTOR DOCTORAL DISSERTATION IN PHYSICS Subject: Atomic and Nuclear Physics Code: 44 01 06 Supervisors: Dr Nguyễn Xuân Hải Assoc Prof Dr Phạm Đình Khang HÀ NỘI - 2018 iii Declaration of Authorship I declare that this thesis titled, “Experimental study on level structure of excited 172 Yb and 153 Sm nuclei using neutron beam from Dalat nuclear research reactor” and the work presented in it are my own under the guidance of my supervisors, and have not been published by anyone else in any other works or articles A part of the results has been published in a peer-review journal and proceeding of 23rd International Seminar on Interaction of Neutrons with Nuclei held in Dubna, Russia written in co-authorship with my supervisors and collaborators The other part is in preliminary, and we expect to collect more experimental data before publishing v Acknowledgements I would like to express my deep gratitude to my supervisors, Dr Nguyễn Xuân Hải and Assoc Prof Dr Phạm Đình Khang for their guidance, support and encouragement during my research work They provided me not only the motivation and the important knowledge, but also the financial support for my life from 2013 to 2015 in Đà Lạt I would like to thank Dr A M Sukhovoj for his great guidance He taught me how to become an honest and effective analyst I would like also to thank Assoc Prof Dr Nguyễn Quang Hưng for his interesting conversations and his important suggestions for my research since 2016 I thank Assoc Prof Dr Nguyễn Mậu Chung, my graduate supervisor for the valuable fundamental knowledge that he gave me during my graduate studies I am grateful to Dalat Nuclear Research Institute and Nuclear Training Center, Vietnam Atomic Energy Institute for their significant supports to my research I also thank my colleagues at Center for Nuclear Physics and Nuclear Electronics, Training and Education Center, and Reactor Center for their kind help during my experiment I am thankful to Ms Nguyễn Thúy Hằng and Ms Nguyễn Thị Diệu Huyền for their kind assistant during my PhD study I also wish to thank Lâm’s photocopy shop, 27 Nguyễn Công Trứ, Đà Lạt, for financial support to print my dissertation Finally, I am deeply indebted to my family for their continuous encouragement and constant confidence in me vii Contents Declaration of Authorship iii Acknowledgements v List of Figures xi List of Tables xv List of Abbreviations xvii Introduction 1 Theory 11 1.1 Compound nuclear reaction 11 1.1.1 Bohr-independence hypothesis 11 1.1.2 Reciprocity theorem 13 1.2 Nuclear level scheme 13 1.3 Nuclear level density 16 1.3.1 Fermi-gas model 18 1.3.1.1 Systematics of the Fermi-gas parameters 21 1.3.1.2 Parity ratio 24 1.3.2 Constant temperature model 25 1.3.3 Gilbert-Cameron model 26 1.3.4 Generalized superfluid model 27 1.3.5 Microscopic-based models 29 1.4 Radiative strength function 33 1.5 Conclusion of chapter 37 viii Experiment and data analysis 39 2.1 39 Experimental facility and experimental method 2.1.1 2.2 2.3 Dalat Nuclear Research Reactor and the neutron beam-port No.3 39 2.1.2 The γ − γ coincidence method 41 2.1.3 γ − γ coincidence spectrometer 44 2.1.3.1 Electronic setup and operation principle 44 2.1.3.2 Main properties 46 2.1.4 Experimental setup and target information 49 2.1.5 Sources of “systematic” errors in γ − γ coincidence method 51 Data Analysis 56 2.2.1 Pre-analysis 57 2.2.2 Two-step cascade spectra 61 2.2.3 Determination of gamma cascade intensity 65 2.2.4 Construction of nuclear level scheme 66 2.2.5 Determination of gamma cascade intensity distributions 67 2.2.6 Extraction of nuclear level density and radiative strength function 69 2.2.6.1 Basic ideas and underlying assumption 69 2.2.6.2 Determination of the functional form of the γ-rays transmission coefficient 72 2.2.6.3 Determination of nuclear level density 76 2.2.6.4 Determination of radiative strength function 78 Conclusion of chapter 79 Results and discussion 3.1 Nuclear level scheme of 172 Yb and 153 Sm 81 81 3.1.1 172 Yb 81 3.1.2 153 Sm 92 3.2 Gamma cascade intensity distributions of 172 Yb 97 3.3 Nuclear level density and radiative strength function of 172 Yb 105 117 List of publications Nguyen Ngoc Anh, Nguyen Xuan Hai, Pham Dinh Khang, Nguyen Quang Hung, Ho Huu Thang, Updated level scheme of 172 Yb from 171 Yb(nth ,γ) reaction studied via gamma–gamma coincidence spectrometer, Nucl Phys A 964 (2017) 55–68 Nguyen Ngoc Anh, Nguyen Xuan Hai, Pham Dinh Khang, Ho Huu Thang, A.M Sukhovoj, L.V Mitsyna, Parameters of cascade gamma decay of 153 Sm compound-states, in proceeding of 23rd International Seminar on Interaction of Neutrons with Nuclei, Dubna, 2015, pp 241–250 Nguyen Ngoc Anh, Nguyen Xuan Hai, Pham Dinh Khang, Ho Huu Thang, First results in the study of level scheme for 172 Yb based on gamma-gamma coincidence spectrometer, Nucl Sci Technol (2016), VINATOM, 6, 26–31 N.A Nguyen, X H Nguyen D K Pham, D C Vu, A M Sukhovoj, L V Mitsyna, Thresholds for the Break of Nucleon Cooper Pairs and Special Features of the Decay of the 172Yb Nucleus in the Reaction 171 Yb(nth ,2γ), to be published on Physics of Atomic Nuclei 119 References [1] T Belgya, O Bersillon, R Capote, T Fukahori, G Zhigang, S Goriely, M Herman, A V Ignatyuk, S Kailas, A Koning, Handbook for calculations of nuclear reaction data, RIPL-2, IAEA TECDOC-1506 IAEA, Vienna URL https://www-nds.iaea.org/RIPL-2/ [2] https://www-nds.iaea.org/public/ensdf_pgm/ [3] S T Boneva, E V Vasil’eva, Y P Popov, A M Sukhovoi, V A Khitrov, Twoquantum cascades of radiative neutron capture Spectroscopy of excited states of complex nuclei in the neutron binding energy region, Fiz Elme Chastits At Yadra 22 (1991) 479 [4] B Singh, Nuclear Data Sheets for A = 172, Nucl Data Sheets 75 (2) (1995) 199–376 [5] R G Helmer, Nuclear data sheets for A = 153, Nucl Data Sheets 107 (3) (2006) 507–788 [6] C W Reich, R C Greenwood, R A Lokken, Decay of 172 Tm: The mixing of Kπ = 0+ and 2+ bands in 172 Yb, Nucl Physics, Sect A 228 (3) (1974) 365–381 [7] T I Kracikova, S Davaa, M Finger, M I Fominykh, W D Hamilton, P O Lipas, E Hammaren, P Toivonen, Nuclear orientation study of the decay of 172 Lu, J Phys G Nucl Phys 10 (8) (1984) 1115–1132 [8] T J Al-Janabi, J D Jafar, S J Hasan, A B Kadhim, K M Mahmood, A J A 120 REFERENCES Azawi, Inelastic scattering cross section of 172,174 Yb using tof technique, Radiat Eff Defects Solids 93 (1) (1986) 273–276 [9] H Youhana, S Al-Obeidi, M Al-Amili, H Abid, A Abdulla, Angular distribution studies in 172,174 Yb, Nucl Phys A 458 (1) (1986) 51–76 [10] J R Cresswell, P D Forsyth, D G E Martin, R C Morgan, H T Alder K, Bohr A, Nuclear structure studies of 172 Yb, J Phys G Nucl Phys (2) (1981) 235–261 [11] R Greenwood, C Reich, S Vegors, Level structure of 171 172 Yb from the Yb(n,γ) reaction, Nucl Phys A 252 (2) (1975) 260–292 [12] W Gelletly, J R Larysz, H G Borner, R F Casten, The reaction 171 Yb(n,γ)172 Yb and the level scheme of 172 Yb, J Phys G Nucl Phys 11 (9) (1985) 1055–1085 [13] A Ataỗ, M Guttormsen, J Rekstad, T Tveter, Gamma decay of 172 Yb after the (ρ,ρ’) inelastic reaction, Nucl Phys A 496 (2) (1989) 255–268 [14] I M Govil, H W Fulbright, D Cline, Collective excitation of 172 Yb from inelastic alpha scattering at 36 MeV, Phys Rev C 36 (4) (1987) 1442–1452 [15] R Tarara, A study of energy level structures of the Ytterbium isotopes 169−175 Yb, Ph.D thesis, Univ Notre Dame (1976) [16] D G Burke, B Elbek, A study of energy levels in even-even ytterbium isotopes by means of (d,p), (d,t), and (d,d’) reactions., Kgl Dan Vidensk Selsk., Mat.-Fys Medd., 36 43p (1967) [17] R O’neil, D Burke, Empirical evidence for Coriolis coupling of octupole states in 172 Yb, Nucl Phys A 182 (2) (1972) 342–358 REFERENCES 121 [18] M Guttormsen, A Ataỗ, K Klungland, S Messelt, T Ramsøy, J Rekstad, ˙ Zelazny, Gross properties of statistical γ-decay in 172 Yb, Nucl T Tveter, Z Phys A 531 (2) (1991) 370–382 [19] D G Burke, I Nowikow, Y K Peng, J C Yanch, Systematics of the (t,p) reaction in Yb and Hf isotopes near the N = 108 "subshell closure", Can J Phys 61 (3) (1983) 460–472 [20] F Ohtani, H Sakaguchi, M Nakamura, T Noro, H Sakamoto, H Ogawa, T Ichihara, M Yosoi, S Kobayashi, Anomaly in the optical potential for deformed nuclei, Phys Rev C 28 (1) (1983) 120–122 [21] T Kruse, W Makofske, H Ogata, W Savin, M Slagowitz, M Williams, P Stoler, Elastic and inelastic proton scattering from heavy collective nuclei, Nucl Phys A 169 (1) (1971) 177–186 [22] A Zilges, P Von Brentano, C Wesselborg, R Heil, U Kneissl, S Lindenstruth, H Pitz, U Seemann, R Stock, Observation of low-lying collective dipole transitions in the rare-earth nuclei 172,174,176 Yb, Nucl Phys A 507 (2) (1990) 399–412 [23] L L Riedinger, E G Funk, J W Mihelich, G S Schilling, A E Rainis, R N Oehlberg, Coulomb excitation of Yb nuclei, Phys Rev C 20 (6) (1979) 2170–2187 [24] C Fahlander, B Varnestig, A Bäcklin, L Svensson, D Disdier, L Kraus, I Linck, N Schulz, J Pedersen, Coulomb excitation of 172 Yb, Nucl Phys A 541 (1) (1992) 157–172 [25] A Schiller, A Voinov, E Algin, J Becker, L Bernstein, P Garrett, M Guttormsen, R Nelson, J Rekstad, S Siem, Low-energy M1 excitation mode in 172 Yb, Phys Lett B 633 (2) (2006) 225–230 122 REFERENCES [26] R C Greenwood, R G Helmer, M H Putnam, K D Watts, Measurement of β-decay intensity distributions of several fission-product isotopes using a total absorption beta-ray spectrometer, Nucl Instruments Methods Phys Res Sect A Accel Spectrometers, Detect Assoc Equip 390 (1-2) (1997) 95– 154 [27] R K Smither, E Bieber, T Von Egidy, W Kaiser, K Wien, Level Scheme of 153 Sm based on (n,γ), (n,e-), and β-Decay experiments, Phys Rev 187 (4) (1969) 1632 [28] M J Bennett, R K Sheline, Y Shida, Levels in 153 Sm, Nucl Phys A 171 (1) (1971) 113–133 [29] I Kanestrøm, P O Tjöm, The level structure of 153 Sm, Nucl Phys A 179 (2) (1972) 305–319 [30] N Blasi, S Micheletti, M Pignanelli, R De Leo, A Gollwitzer, S Deylitz, B D Valnion, G Graw, L A Malov, Study of 153 Sm via the 154 Sm(p,d) reaction, Nucl Phys A 624 (3) (1997) 433–448 [31] J R Lien, G Løvhøiden, J Rekstad, A Henriques, C Gaarde, J S Larsen, S Y Van Der Werf, High-spin particle states in 153 Sm studied with the (α,3 He) reaction, Nucl Phys A 412 (1) (1984) 92–100 [32] D G Burke, I G Nowikow, Nuclear structure studies and particle–rotor model tests for 151,153 Sm using 149,151 Sm(t,p) reactions, Nucl Phys A 756 (34) (2005) 308–324 [33] A V Ignatyuk, J L Weil, S Raman, S Kahane, Density of discrete levels in 116 Sn, Phys Rev C 47 (4) (1993) 1504 [34] P E Garrett, H Lehmann, J Jolie, C A McGrath, M Yeh, W Younes, S W REFERENCES 123 Yates, Properties of 112 Cd from the (n,n’γ) reaction: Levels and level densities, Phys Rev C 64 (2) (2001) 24316 [35] A Gilbert, A G W Cameron, A composite nuclear-level density formula with shell corrections, Can J Phys 43 (8) (1965) 1446–1496 [36] A L Caraley, B P Henry, J P Lestone, R Vandenbosch, Investigation of the level density parameter using evaporative α-particle spectra from the 19 F + 181 Ta reaction, Phys Rev C 62 (5) (2000) 54612 [37] G M Gurevich, L E Lazareva, V M Mazur, S Y Merkulov, G V Solodukhov, V A Tyutin, Total nuclear photoabsorption cross sections in the region 150< A< 190, Nucl Phys A 351 (2) (1981) 257–268 [38] F Beˇcváˇr, P Cejnar, J Honzátko, K Koneˇcný, I Tomandl, R E Chrien, E1 and M1 strengths studied from two-step γ cascades following capture of thermal neutrons in 162 Dy, Phys Rev C 52 (3) (1995) 1278–1294 [39] G A Bartholomew, I Bergqvist, E D Earle, A J Ferguson, Intensity anomaly in the (d,pγ) reaction, Can J Phys 48 (6) (1970) 687–708 [40] A Schiller, L Bergholt, M Guttormsen, E Melby, J Rekstad, S Siem, Extraction of level density and γ strength function from primary γ spectra, Nucl Instruments Methods Phys Res Sect A Accel Spectrometers, Detect Assoc Equip 447 (3) (2000) 498–511 [41] A C Larsen, M Guttormsen, M Krtiˇcka, E Bˇeták, A Bürger, A Görgen, H T Nyhus, J Rekstad, A Schiller, S Siem, H K Toft, G M Tveten, A V Voinov, K Wikan, Analysis of possible systematic errors in the Oslo method, Phys Rev C 83 (3) (2011) 034315 [42] http://www.mn.uio.no/fysikk/english/research/about/infrastructure/ OCL/nuclear-physics-research/compilation/ 124 REFERENCES [43] E V Vasilieva, A M Sukhovoj, V A Khitrov, Direct experimental estimate of parameters that determine the cascade gamma decay of compound states of heavy nuclei, Phys At Nucl 64 (2) (2001) 153–168 [44] A M Sukhovoj, New model of the cascade gamma decay of neutron resonances for practitioners: Basic concepts and attainable precision, Phys At Nucl 78 (2) (2015) 230–245 [45] A M Sukhovoj, L V Mitsyna, N Jovancevic, Overall picture of the cascade gamma decay of neutron resonances within a modified practical model, Phys At Nucl 79 (3) (2016) 313–325 [46] A M Sukhovoj, V A Khitrov, Level density and radiative strength functions from (nth ,2γ) reactions and basic properties of the 96 Mo nucleus, Phys At Nucl 72 (9) (2009) 1426–1434 [47] N A Son, Mật độ mức hàm lực thực nghiệm hạt nhân 49 Ti, 52 V 59 Ni, Ph.D thesis, Vietnam Atomic Energy Institute (2013) [48] N A Son, P D Khang, N D Hoa, V H Tan, N X Hai, D Lanh, P N Son, H H Thang, Determining Experimental Transition Strengths of 52 V by Two-Step Gamma Cascades, Int Organ Sci Res J Eng Vol 16–21 [49] N X Hai, Ứng dụng phương pháp cộng biên độ xung trùng phùng nghiên cứu phân rã gamma nối tầng hạt nhân Yb Sm lò phản ứng hạt nhân Đà Lạt, Ph.D thesis, Ministry of Education and Training of Vietnam (2010) [50] J M Blatt, V F Weisskopf, Theoretical nuclear physics, John Wiley & Sons, 1952 [51] G E Mitchell, A Richter, H A Weidenmüller, Random matrices and chaos in nuclear physics: Nuclear reactions, Rev Mod Phys 82 (4) (2010) 2845 REFERENCES 125 [52] H A Weidenmüller, G E Mitchell, Random matrices and chaos in nuclear physics: Nuclear structure, Rev Mod Phys 81 (2) (2009) 539 [53] N Bohr, Neutron capture and nuclear constitution, Nature 137 (3461) (1936) 344–348 [54] G Molnar, T Belgya, B Fazekas, Complete Spectroscopy of Discrete Nuclear Level, INDC(NDS)-335, IAEA, Vienna (1995) 97 [55] A Voinov, A Schiller, M Guttormsen, J Rekstad, S Siem, Determination of the electromagnetic character of soft dipole modes solely based on quasicontinuous γ spectroscopy, Nucl Instruments Methods Phys Res Sect A Accel Spectrometers, Detect Assoc Equip 497 (2-3) (2003) 350–358 [56] H A Bethe, An attempt to calculate the number of energy levels of a heavy nucleus, Phys Rev 50 (4) (1936) 332 [57] A Gilbert, F S Chen, A G W Cameron, Level densities in lighter nuclei, Can J Phys 43 (7) (1965) 1248–1258 [58] A V Voinov, B M Oginni, S M Grimes, C R Brune, M Guttormsen, A C Larsen, T N Massey, A Schiller, S Siem, Nuclear excitations at constant temperature, Phys Rev C 79 (3) (2009) 31301 [59] A V Ignatyuk, IAEA Report INDC (CCP)-233 L (IAEA, Vienna) [60] P Demetriou, S Goriely, Microscopic nuclear level densities for practical applications, Nucl Phys A 695 (1-4) (2001) 95–108 [61] N Quang Hung, N Dinh Dang, L Quynh Huong, Simultaneous Microscopic Description of Nuclear Level Density and Radiative Strength Function, Phys Rev Lett 118 (2) (2017) 022502 [62] T Von Egidy, H H Schmidt, A N Behkami, Nuclear level densities and level spacing distributions: Part II, Nucl Phys A 481 (2) (1988) 189–206 126 REFERENCES [63] T Ericson, The statistical model and nuclear level densities, Adv Phys (36) (1960) 425–511 [64] J H D Jensen, J M Luttinger, Angular Momentum Distributions in the Thomas-Fermi Model, Phys Rev 86 (6) (1952) 907 [65] A G W Cameron, Nuclear level spacings, Can J Phys 36 (8) (1958) 1040– 1057 [66] W Dilg, W Schantl, H Vonach, M Uhl, Level density parameters for the back-shifted fermi gas model in the mass range ∼ 40 < A