Systematics of the shears mechanism in silver isotopes

Abstract

A systematic investigation of the shears mechanism in silver isotopes has been carried out. Lifetimes have been measured by means of the Doppler-shift attenuation method for states in two magnetic dipole (M1) bands in 105 Ag and one each in 103 Ag and 106 Ag. Experimental total angular momenta and reduced transition strengths for these bands have been compared with the predictions of the tilted axis cranking (TAC) model with configurations involving one g 9/2 proton and quasineutrons from the h 11/2 and g 7/2 or d 5/2 orbitals. There is good overall agreement for both the total angular momenta and reduced transition strengths. The deduced B(M1) strengths, which are a sensitive probe of magnetic rotation, show a decrease consistent with TAC predictions for one M1 band in 105 Ag and in 106 Ag, confirming the shears mechanism as the means of excitation. Furthermore, the staggering in the transition energies in 103 Ag and absence of regular sequences of M1 transitions for N 56 suggest that N = 56 is the lower boundary for the appearance of the shears mechanism in this mass region.

Energy staggering parameters in nuclear magnetic rotational bands *

“…The Dirac equation for the nucleons is solved in a three-dimensional harmonic oscillator basis and a basis of 10 major oscillator shells is adopted. The calculated rotational excitation energies, total angular momenta and B(M 1) values in comparison with the corresponding data [20,66,67] are shown in Fig. 4.…”

“…In the 110, 130 and 190 mass regions, the MR bands in even-even, odd-odd and odd-A nuclei are presented respectively. The corresponding data are taken from the previous review [12] and recent observations [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][56][57][58]. [12] and recent observations [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][56][57][58].…”

“…The corresponding data are taken from the previous review Ref [12]. and recent observations[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][56][57][58].…”

“…The transition from chiral rotation to magnetic rotationTaking the M 1 bands in 103 Rh[65], 105 Ag[20,66,67], and 107 In[24,68] with the same configuration πg −1 9/2 ⊗ νh1 11/2 (g 7/2 /d 5/2 ) 1 as examples, the extracted experimental S(I) values are shown and compared in Fig.3.…”

Lifetime measurements and magnetic rotation in107Ag

“…Magnetic rotational or antimagnetic bands have been identified in Rh, Ag, Cd, In, Sn, and Sb isotopes in the A ≈ 110 mass region where the nuclei involve coupling of one or more proton holes in the high-g 9/2 orbitals with neutrons in the low-g 7/2 , d 5/2 , and h 11/2 orbitals. Magnetic rotational bands are also expected in 107 Ag, in addition to 103−106 Ag [3][4][5][6][7] and 109 Ag [8] in Ag isotopes. The level scheme of 107 Ag has been reported previously [9][10][11].…”