DISCOVERY OF MULTIPLE,COLLECTIVE BAND STRUCTURES IN NUCLEI WITH A=60—80

  • Recent studies of levels in even-even 68,70,72Ge,70,72,74Se,74,76,78,80Kr and 65Ga and 74Br have led to the discovery of a wide variety of different collective band structures.These include bands built on near spherical ground states and excited more well de-formed shapes that may include triaxial shapes,rotation-aligned bands built on thesame orbital (g(9/2)2 for both protons and neutrons,RAL negative parity bands witheven and odd spins,and ΔI=1 γ-type vibrational bands in even-even nuclei.As recent as 1974,a survey of the energy level in the even-even Ge and Se iso-topes[1] revealed little was known above a spin of 4+ (see for examples Figs.1 and 2 of Ref.1).With the exception of the unusally low-lying excited 0+ states in 70,72Ge,first discovered in 72Ge in 1948 at Vanderbilt[2],the theoretical treatment of thesenuclei was limited primarily to some variation of the vibrational model.However,very recently there has been a surge of information on nuclei in this region that hasrevealed fascinating new features and also provided new insight into the excited 0+’states.Particularly striking are the multiple,independent and highly collective bandstructures which we have discovered in our in-beam γ-ray spectroscopy studies fol-lowing heavy-ion induced reaction.Evidence for and the theoretical understandingof the richness of the collective band structures that are found in our studies of68,70,72Ge (Refs.3—6),70,72,74Se (Refs.7—13) and 74,76,78,80Kr (Refs.14—18),as illustratedby the at least seven different bands found in our studies of the levels of 68Ge 74Se,and 76Kr (Figs.1—3),are described in this paper.These multiple structures includethe following:a) coexistence of ground bands built on near-spherical shapes andexcited bands with larger deformation built on O+′ band heads;b) bands with 8+ band heads interpreted as rotation-aligned,RAL,bands built on both neutron and/orproton (g(9/2)2 quasiparticle configurations coexisting with the ground-state band;c)RAL neutron and proton odd-parity bands formed from coupling of a g(9/2 quasipar-ticle and a p(1/2),p(3/2) or f(5/2),quasiparticle with the core;d) ΔI=1 even-parity bands,which are best characterized as gamma-vibrational bands;and e) additional bandswhose nature are presently not known.
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  • [1] A. V. Ramayya and J. H. Hamilton, Proc. international Conf. on Gamma Ray Transition Probabilities, eds. S. C. Pancholi and S. L Gupta. U. Delhi Press (1977), P. 123.[2] S. K. Haynes. Phys. Rev., 73(1948). 187; 74 (1948), 423.[3] A. de Lima, B. van Nooijen. R. M. Ronningen, H. Kawakami, J. H. Hamilton. A. V. Ramay-ya, R. B. Piereey, R. L. Robinson. H. J. Kim and W. K. Tuttle, Selected Topies in Nuelear Strueture, ed., V. G. Soloviev et al., Dubna, USSR. Vol. 1 (1976), 194.[4] A. de Lima, J. H. Hamilton, A. V. Ramayya, B. van Nooijen, R. M. Ronningen. H. Hawa-kami, R. B. Piercey, R. L. Robinson, H. J. Kim, W. K. Tuttle and L. K. Peker. Int. Conf. on Nucl. Phys., Contributed Papers, Tokyo (1977), 276.[5] R. L. Robinson, H. J. Kim, R. O. Sayer, J. C. Wells, R. M. Ronningen and J. H. Hamilton, Phys. Rev., C16 (1977),2268.[6] A. C. Rester, A. P. do Lima, J. H. Hamilton, A. V. Ramayya, H, Kawakami, E. de Limn, R. M. Ronningen, R. L. Robinson and H. J. Kim, Contributed papers, Int. Conf. on Nucl. Structure, Tokyo (1977), 281,[7] A. V. Ramyya, J. H. Hamilton, R. L. Robinson, H. Hawakami, R. B. Fiercey, C. F. Maguire, W. T. Pinkston, A. P. de Lima, D. L. Sastry, H. J. Kim, J. C. Wells and A. C. Rester, Contri-buted Papers; Int. Conf. on Nucl. Structure, Tokyo (1877), 280.[8] J. H, Hamilton, A. V. Ramayya, W. T. Pinkston, R. M. Ronningen, G. Garcia-Bermudez. H. K. Carter, R. L. Robinson, H. J, Kim and R. O. Sayer, Phys. Rev. Lett., 32 (1974), 239.[9] J. H. Hamilton, H. L. Crowell. H. L. Robinson, A. V. Ramayya, W. E. Collins, R. M. Ron-ningen, V. Maruhn-Rezwani, J. A. Maruhn, N. C. Singhal, H. J. Kim, R. O. Sayer, T. Magee and L. C. Whitlock, Phys. Rev. Lett., 36 (1976), 340.[10] A. V. Ramayya, R. M, Ronningen, J. H. Hamilton, W. T. Pinkston, G. Careia-Bermudez. R. L. Robinson, H. J. Kim, H. K. Carter and W. E. Collins, Phys. Rev., C12 (1975), 1360.[11] R. M. Ronningen, A. V. Ramayya. J. H. Hamilton, W. Lourens, J. Lange, H, K. Carter and R. O. Bayer, Nucl. Phys., A261 (1976), 439.[12] R. B. Piercey, A. V. Ramayya. R. M. Ronningen, J. H. Hamilton, R. L. Robinson and H. J. Kim, Phys, Rev. Lett., 37 (1976), 496.[13] R B. Piercey, Ph. D. Thesis, Vanderbilt University (1917) and R. B. Piercey R. M. Ronningen, J. H. Hamilton, V. Maruhn-Rezwanl, R. L. Robinson and H. J. Kim, to be published in Phys. Rev.[14] R. Soundranayagam, R. B. Piercey, J. H. Hamilton, A. V. Ramayya, C. F. Maguire, R. L. Ro-binson and H. J. Kim, Bull. Southeastern Section Am. Phys. Soc. Meeting 45 (1978), 20.[15] R .B. Piercey, A. V. Ramayya, J, H. Hamilton, C. F. Maguire, R. L. Hobinson and J. C. Wells, contribution to the Int. Conference in Canberra (1978).[16] R. L. Robinson, H. J, Kim, R. O. Sayer, R. B. Piercey, A. V. Ramayya, J. H. Hamilton and J. C. Wells, Bull. Am, Phys. Soc. 22 (1977), 1027. and contribution to the International Conference in Canberra (1978).[17] D, L, Sastry, A. Ahmed, A. V. Ramayya, R. L. Robinson, R. B. Piercey, J. H. Hamilton, C. F. 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Funkc, Acad. of Science DDR, Rossendorf ZfK-336, Dresden (2977), 14.[23] J. F. Brouandet, B. Berther, C. Morand, A. Giorni, J, P. Longequeue and T. V. Chang, Phys. Rev., C14 (1976), 103.[24] D. G. McCauley and J. E. Draper, Phys. Rev., C4 (1971), 475.[25] H. P. Hellmeistcr, J. Keinover, K. P. Lieb, R. Rascher, R. Ballini, J. Delaunoy and H. Du-mont, contribution to the International Conf. in Canberra (1978).[26] L. K. Peker and J. H. Hamilton, Int, Conf. on Nucl. Structure, Contributed Papers, Tokyo (1977), 110.[27] A, Bohr and B. R. Mottelson, Supp. J. Phys. Soc. Japan 44 (1978), 157.[28] L. K. Peker, J. O. Rasmussen and J. H. Hamilton, submitted to Phys. Rev. Letters.[29] J. H. Hamilton, Proc. Int. Conf. on Selected Topics in Nucl. Structure, eds. V, G. Soloviev, et al., Dubna, USSR (1976), Vol. II, 303.[30] F. S. Stephens and R. S. Simon, Nucl. Phys., A183 (1972), 257.[31] C. Flaum and D. Cline, Phys. Rev., 14 (1976), 1224,[32] A. P, de Lima et a1., contribution to the Int. Conf, in Canberra (1978).[33] E. Nolte, Y. Shida, W, Kutschera, P. Prestele and H. Morinaga, Z. Phys. 268 (1974), 267.(34] I. Kh. Lemberg et al., Proc. Nucl. Structure Conf., Soviet Acad. of Science, Leningrad (1975), p. 379.[35] L. K. Peker, Proc. Winter School for Nucl. Theory and High Energy Phys., Leningrad, USSR (1974), 334 and (1975).[36] A, Faessler, M. Ploszajczak and K. R. Sandhya Devi, Int. Symp. on. High Spin States and Nucl. Structures, ed., L. Funke, Akademic Der Wisserschafter Der DDR, ZfK-336, 1977, p. 68 and to be published; and A. Faessler et al., Nucl. Phys.. A286 (1977), 101.[37] C. Flaum, D. Cline, A. W. Sunyar and O. C. Kistner, Phys. Rev. Lett., 33 (1974), 973; C. Flaum et al., Nucl. Phys, A264 (1976), 291.[38] J. A. Grau, L. E. Samuelson, F. A. RiekeY, P. C. Simms and G. J. Smith, Phys. Rev., C14 (1676), 2297.[39] B. Reehal and R. Sorensen, Phys. Rev., C2 (1970), 819.[40] C. Merand, J. F. Bruandet, A. Giorni and T. V. Chang, J. Phys. 38 (1977), 1319.[41] V. G. Kiptiliy, M. F. Kudojarov, A. S. Mishin, I. Kh. Lemberg, A. A. Pasternak, Int. Symp. on. High Spin States and Nucl. Struclure, ed.; L. Funke, Academy of Science, Central Institute for Nuelear Research, Rossendorf, Dresden (1977), 12.[42] K. P. Lieb and J. J. Kolata. Phys. Rev, C15 (1977), 939.[43] D, Ward, Int. Conf on Reactions Between Complex Nuolei, eds., R. L., Robinson et al., Nashville, VoI. II (1974), 417.[44] V, S. Zvonov and V. E. Mitoahin, Int. Symp. on High Spin Phenomena and Nucl. Structure, ed., L. Funke, ZfK-336, Rossendorf, Dresden. (1977), 1.[45] G. Gnenss and W. Greiner, Nucl. Phys., A171 (1971), 449.[46] K. Kumar, R. Remaud, P. Aguer, J. S. Vaagen, A. C. Rester, R. Foucher and J. H, Hamil-ton, Phys. Rev., C16 (1977), 1235.[47] K. Kumar, private communication to be published.[48] W. Greiner, private communication of earlier work, International Conference, Canberra (I978)[49] D. Ardouin, R. Tamisier, M. Vergnes, G. Rotbard, J. Kalifa, G. Berrier and B. Grammaticos. 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R.L.Robinson and A.V.Ramayya. DISCOVERY OF MULTIPLE,COLLECTIVE BAND STRUCTURES IN NUCLEI WITH A=60—80[J]. Chinese Physics C, 1979, 3(3): 355-381.
R.L.Robinson and A.V.Ramayya. DISCOVERY OF MULTIPLE,COLLECTIVE BAND STRUCTURES IN NUCLEI WITH A=60—80[J]. Chinese Physics C, 1979, 3(3): 355-381. shu
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DISCOVERY OF MULTIPLE,COLLECTIVE BAND STRUCTURES IN NUCLEI WITH A=60—80

Abstract: Recent studies of levels in even-even 68,70,72Ge,70,72,74Se,74,76,78,80Kr and 65Ga and 74Br have led to the discovery of a wide variety of different collective band structures.These include bands built on near spherical ground states and excited more well de-formed shapes that may include triaxial shapes,rotation-aligned bands built on thesame orbital (g(9/2)2 for both protons and neutrons,RAL negative parity bands witheven and odd spins,and ΔI=1 γ-type vibrational bands in even-even nuclei.As recent as 1974,a survey of the energy level in the even-even Ge and Se iso-topes[1] revealed little was known above a spin of 4+ (see for examples Figs.1 and 2 of Ref.1).With the exception of the unusally low-lying excited 0+ states in 70,72Ge,first discovered in 72Ge in 1948 at Vanderbilt[2],the theoretical treatment of thesenuclei was limited primarily to some variation of the vibrational model.However,very recently there has been a surge of information on nuclei in this region that hasrevealed fascinating new features and also provided new insight into the excited 0+’states.Particularly striking are the multiple,independent and highly collective bandstructures which we have discovered in our in-beam γ-ray spectroscopy studies fol-lowing heavy-ion induced reaction.Evidence for and the theoretical understandingof the richness of the collective band structures that are found in our studies of68,70,72Ge (Refs.3—6),70,72,74Se (Refs.7—13) and 74,76,78,80Kr (Refs.14—18),as illustratedby the at least seven different bands found in our studies of the levels of 68Ge 74Se,and 76Kr (Figs.1—3),are described in this paper.These multiple structures includethe following:a) coexistence of ground bands built on near-spherical shapes andexcited bands with larger deformation built on O+′ band heads;b) bands with 8+ band heads interpreted as rotation-aligned,RAL,bands built on both neutron and/orproton (g(9/2)2 quasiparticle configurations coexisting with the ground-state band;c)RAL neutron and proton odd-parity bands formed from coupling of a g(9/2 quasipar-ticle and a p(1/2),p(3/2) or f(5/2),quasiparticle with the core;d) ΔI=1 even-parity bands,which are best characterized as gamma-vibrational bands;and e) additional bandswhose nature are presently not known.

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