271 COMMENTS 00NDS 200006 271 H TYP=FUL$AUT=R.B. Firestone, and J. Gilat$CIT=NDS 90, 391 (2000)$ 271 2 H CUT=1-Apr-2000$ 271 C TITL$Evaluation for A=271 271 c AUTH$R.B. Firestone, and J. Gilat 271 c INST$Nuclear Science Division 271 #c Lawrence Berkeley National Laboratory 271 #c 1 Cyclotron Road 271 #c Berkeley, California 94720 271 c ABST$These data are mainly from cold fusion experiments performed at 271 2c GSI/Ship, Dubna, and Berkeley. The experiments generally involve mass 271 3c separation of heavy elements followed by implantation into a 271 4c position-sensitive alpha-particle detector. The position, energy, and 271 5c time with respect to implantation are recorded. Successive decays at a 271 6c given position are correlated into a decay chain linking the heaviest 271 7c cold fusion product to lighter nuclei which also may be previously 271 8c unknown. In some cases the decay chain ends in spontaneous fission, 271 9c and some alpha particles escape the detector leaving only partial 271 ac energy signals. When multiple alpha decay chains are observed for a 271 bc given parent, the evaluators have made subjective assignments to 271 cc isomer and ground states based on comparable alpha particle energies 271 dc and decay times. 271 c CUT$April 1, 2000 271 C CIT$NDS 90, 391 (2000) 271 c COMM$Significant use is made of alpha energy and half-life calcuations 271 2c in making isotope assignments. The decay chains starting at A=289 and 271 3c A=293 are not connected to known nuclei and are assigned, in part, on 271 4c the basis of reaction systematics. The evaluators have made extensive 271 5c use of calculated masses and lifetimes from 1997Mo25. These authors 271 6c calculate alpha-decay lifetimes using the Viola-Seaborg relation 271 8c log(T{-1/2}(|a))=(aZ + b)|*Q(|a){+1/2} +(cZ + d) where T{-1/2}(|a) is 271 ac in seconds, Q(|a) in MeV, and a=1.66175, b=-8.5166, c=-0.20228, and 271 bc d=-33.9069. 271 c Various spin and parity assignments have been proposed for the these 271 2c superheavy elements. Some of the suggested values are provided by the 271 3c evaluators without comment. The reader is referred to the original 271 4c publications for details. From Nilsson model calculations (1996FiZY), 271 5c at zero deformation there is a shell gap at Z=114 but no strong 271 6c neutron shell gap for N>126. The available single-particle shell model 271 7c states at Z<114 are 2f7/2, 1i13/2, and 1h9/2, and for Z>114 2f5/2 and 271 8c 3p3/2. The expected order of shell model neutron states for N>126 is 271 9c 2g9/2, 1i11/2, 1j15/2, 3d5/2, 2g7/2, 4s1/2, 3d3/2, and 2h11/2. In the 271 ac case of a finite deformation, the theoretical level structure picture 271 bc becomes much more complex. The data are too limited to distinguish the 271 cc various configurations. However, there are numerous instances of 271 dc isomerism consistent with the wide range of available spin states. 271 ec There is also strong evidence of alpha decay to excited states 271 fc indicating that ground state structure may change substantially from 271 gc parent to daughter. The evaluators emphasize that there is too little 271 hc data available to infer Q(|b{+-})values and assign isotope and isomer 271 ic levels with great confidence. 271 c These evaluations are dedicated to the memory of Glenn Seaborg. 271 REFERENCES 200006 271 R 1995AU04 JOUR NUPAB 595 409 271 R 1995HO27 JOUR RAACA 70/71 135 271 R 1996FIZY BOOK Table of Isotopes, 8th Ed., John Wiley and Sons 271 R 1996HE07 JOUR PRVCA 53 1892 271 R 1997AU04 JOUR NUPAB 624 1 271 R 1997MO25 JOUR ADNDA 66 131 271 R 1997SM03 JOUR PRVCA 56 812 271DS ADOPTED LEVELS 00NDS 200006 271DS H TYP=MOD$AUT=B. SINGH$DAT=23-FEB-2004$COM=SYMBOL 271DS2 H DS SUBSTITUTED FOR Z=110 271DS H TYP=FUL$AUT=R.B. Firestone, and J. Gilat$CIT=NDS 90, 391 (2000)$ 271DS2 H CUT=1-APR-2000$ 271DS c 1996He07: GSI/SHIP cold fusion experiment, {+208}Pb({+64}Ni,n). 271DS2c Observed nine position and time correlated chains of |a particle 271DS3c events. Determined |a energies and time intervals between 271DS4c successive particles. Assigned to decay of {+271}Ds by consistency of 271DS5c lower chain member energies and lifetimes with known No and Rf data. 271DS6c The measured |a energies and emission times are grouped by 271DS7c evaluator as follows: 271DS8c five events with an average energy of E1=10740 {I20} keV, two events 271DS9c with an average energy of E2=10680 {I20} keV, and one event with energy 271DSAc E3=10710 {I20} keV. The emission times for the first two groups were 271DSBc 0.2-4.4 ms and 81 ms for the last event, suggesting two parents and 271DSCc two daughter states. A simple interpretation consistent 271DSDc with the data is to assume that the longer lived (T{-1/2}=0.06 s) 271DSEc parent state is the 0+x or g.s. of {+271}Ds, and an isomeric |a 271DSFc emitting state lies 30+x 20 keV higher. 271DS Q -6080 CA 6700 SY 2300 SY 10900 SY 1995AU04,1997MO25 271DS cQ QA$from 1995Au04: if 10710 {I20} keV |a populates the ground state, 271DS2cQ Q(|a)=10870 {I20}. 271DS L 0+X 0.06 S +27-3 271DS2 L %A=100 271DS cL T$from 1996He07, maximum likelihood method. 271DS cL J$1997Mo25 calculate J|p=3/2+ which is not consistent with the 271DS2cL assignments of 1996He07 (9/2+) and 1997Au04 (11/2-). 271DS cL %A$predicted |b (1997Mo25) and SF (1995Ho27,1997Sm03) half-lives 271DS2cL much longer than those predicted and observed for |a emission. 271DS3cL No spontaneous fission events observed in 1996He07. 271DS L 30+X 30 1.1 MS +6-3 M 271DS2 L %A=100 271DS cL T$from 1996He07. Unweighted average of seven events. 271DS cL %A$predicted |b (1997Mo25) and SF (1995Ho27,1997Sm03) half-lives are 271DS2cL much longer than those predicted and observed for |a emission. 271DS3cL No spontaneous fission events observed in 1996He07.