2004Ga29: The study was carried out at the Sector Focus Cyclotron of the Heavy Ion Research Facility (HIRFL), Lanzhou, China by a Chinese collaboration. The reaction used was ²⁴³Am(²⁶Mg,4n). The reaction cross-section is not provided. The ²⁶Mg⁸⁺ ions were produced at a beam energy of 168 MeV corresponding to approximately 6.5 Mev/u. The experiment ran for about 250 hours. The current is quoted in units of "1.0 μA " and the total projectile dose is not given. Evaluator notes that the energy at target centre and excitation energy for CN formation are not quoted. The experimental set-up included a new collection and measurement apparatus. The transport time from the target to the point of measurement was 0.3 secs with a quoted transport efficiency of about 70%. α total of four pairs of PIPS detectors were used with an active area of 200 mm² for measuring the energy of α particles. Energy resolution was about 40 keV and 100 keV respectively for the top and bottom detectors. The parent-daughter searching mode for α-α correlations was employed. Every 5 secs, the wheel was double-stepped in the parent mode. Following a signal, the daughter mode was implemented after a single step or for an interval of 10 secs. No estimates for randomness are provided and only parent-daughter events were looked for. The system spent about 2% of the time in daughter mode which was triggered about 2000 times. Six events were detected in α-α mode and attributed to ²⁶⁵Bh and its daughter ²⁶¹Db. Two more events in α-α-α mode were also reported attributed to ²⁶⁵Bh, daughter ²⁶¹Db and grand-daughter ²⁵⁷Lr. The experimenters state that they did not analyze the half-life of ²⁵⁷Lr due to the small number of events. The evaluator points out that since only parent-daughter events were looked for and in the absence of any estimates of randomness, it appears that the observation of ²⁵⁷Lr cannot be regarded with confidence. The evaluator further notes that the experimental set-up did not appear to be sensitive to the detection of SF events. As a result, no SF events were measured, had they occurred.

Other: 1995Sc53 carried out a radiochemical search using the reaction ¹⁶O+²⁵⁴Es at the Cyclotron facility at LBL. No events could be attributed to this nucleus.

Theory: see Nuclear Science References.

Assignment: produced by ²⁴³Am(²⁶Mg,4n) E=168 MeV (2004Ga29). Eα=8930 keV 40 and T_1/2=1.70 s +79-49 assigned to ²⁶¹Db are consistent with Eα=8930 keV and T_1/2=1.8 s 4 adopted by 1999Ar21; however, Eα=8881 keV (unweighted average) and T_1/2=2.1 s +38-9 (estimated by the evaluator using the method of 1984Sc13) for the two events assigned to ²⁵⁷Lr are SOMEWHAT discrepant with Eα=8861 keV 12 and 8796 keV 12 with T_1/2=0.646 s 25 adopted by 1999Ar21. In addition, the overall efficiency of the system for detecting the parent and correlated alpha-decay events is not reported. This factor assumes significance given the relatively large time step of five seconds for the parent mode when compared with the expected alpha-decay half-life of ²⁶⁵Bh. The absence of any mention of key experimental quantities such as the total projectile dose, the production cross-section or excitation function measurements and a probability or random analysis, adds to the ambiguity of this work. Therefore, the assignment to ²⁶⁵Bh is considered to be tentative.