ADOPTED LEVELS for 260Md

Author: Y. A. Akovali |  Citation: Nucl. Data Sheets 87, 301 (1999) |  Cutoff date: 1-Oct-1998 

 Full ENSDF file | Adopted Levels (PDF version) 


Q(β-)=9.E2 keV SYS(n)= 5.1×103 keV SYS(p)= 4.4×103 keV SYQ(α)= 6.9×103 keV SY
Reference: 2012WA38

General Comments:

Assignment: 254Es(105-MeV 18O,x), 254Es(126-MeV 22Ne,x); mass separated (1986Lo16). Isotope assignment was made by 1986Lo16 from cross-section results and from known and predicted decay properties for possible isotopes with α=260: the measured cross sections were consistent with production of 260No, 260Md or 260Lr; since 260Lr is a 180S α emitter, 260No has a half-life of 106 ms, the observed 31.8-d SF activity was not from 260Lr or 260No.

Possibility of observed fission activity being from 260No following β- decay was ruled out by 1986Lo16 by measuring time correlations between β- and SF activities.

Possibility of the observed fission activities being from 256Fm (following α decay of 260Md to 256Es which β- decays to 256Fm) was also considered by 1986Lo16. The mass and total kinetic energy distributions of fission fragments were found to be very different than those for 256Fm, indicating that most of the observed fission activities were not from 256Fm.

Q-value: Note: Current evaluation has used the following Q record




E(level)
(keV)
T1/2(level)
  0.0 31.8 d 5 
% SF ≥ 42
% β- ≤ 10
% ε ≤ 23
% α ≤ 25

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Additional Level Data and Comments:

E(level)Jπ(level)T1/2(level)Comments
  0.0 31.8 d 5 
% SF ≥ 42
% β- ≤ 10
% ε ≤ 23
% α ≤ 25
An upper limit of 25% α branching was deduced by 1986Lo16 by fitting the fission distributions for mass 260 with a previously known distribution for 256Fm; an upper limit of 10% was deduced for β- decay from correlation counts for β- and SF events. Upper limits for K and L captures were obtained by 1989Hu09 as 10% each by time-correlation measurements of Fm x-rays with possible SF events from 260Fm, provided that T1/2(260Fm)<100 ms. Inclusion of M+N+ shells yields %ε<23.
E(level): An upper limit of 25% α branching was deduced by 1986Lo16 by fitting the fission distributions for mass 260 with a previously known distribution for 256Fm; an upper limit of 10% was deduced for β- decay from correlation counts for β- and SF events. Upper limits for K and L captures were obtained by 1989Hu09 as 10% each by time-correlation measurements of Fm x-rays with possible SF events from 260Fm, provided that T1/2(260Fm)<100 ms. Inclusion of M+N+ shells yields %ε<23.

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