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Title: Coexistence of single-particle and collective excitation in Ni 61

Journal Article · · Physical Review. C
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [1];  [1]; ORCiD logo [1];  [2];  [3]; ORCiD logo [4]; ORCiD logo [5]; ORCiD logo [6]
  1. Florida State Univ., Tallahassee, FL (United States)
  2. Federal Office for Radiation Protection (Germany)
  3. Japan Atomic Energy Agency (JAEA), Tokai (Japan); Univ. of Tokyo (Japan)
  4. Univ. of Tsukuba (Japan)
  5. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Physics Division
  6. Department of Atomic Energy (India). Variable Energy Cyclotron Centre (VECC)

Here, the high-spin states in 61Ni have been studied using the fusion evaporation reaction, 50Ti(14C, 3n)61Ni at an incident beam energy of 40 MeV. A Compton suppressed multi-HPGe detector setup, consisting of six clover detectors and three single-crystal HPGe detectors, was used to detect the de-exciting $$\gamma$$ rays from the excited states. The level scheme has been extended up to an excitation energy of 12.8 MeV and a tentative Jπ=35/2+. The low-lying negative parity levels are found to be generated by single-particle excitation within the fp shell and also excitations to the g9/2 orbitals as explained well with shell model calculations using the GXPF1Br+VMU (modified) interaction. Two rotational structures of regular E2 sequences with small to moderate axial deformation have been established at higher excitation energy. Most interestingly, two sequences of M1 transitions are reported for the first time and described as magnetic rotational bands. The shears mechanism for both the bands can be described satisfactorily by the geometrical model. The shell model calculation involving the cross shell excitation beyond the fp shell well reproduce the M1 and E2 sequences. The shell model predicted B(M1) values for the magnetic rotational band B1 show the decreasing trend with spin as expected with closing of the shears.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Nuclear Physics (NP); National Science Foundation (NSF); Centaur Center of Excellence; Japan Society for the Promotion of Science (JSPS)
Grant/Contract Number:
AC05-00OR22725; SC0009883; PHY-1401574; PHY-1712953; PHY-2012522; NA0003841; 20K03981; 17K05433
OSTI ID:
1975330
Journal Information:
Physical Review. C, Vol. 107, Issue 5; ISSN 2469-9985
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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