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Topic: element 117  (Read 13478 times)

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Offline gippgig

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element 117
« on: June 09, 2008, 12:32:24 AM »
According to their web site, JINR will try to make element 117 in the fall by bombarding 243Am with 50Ti. Why not 249Bk + 48Ca?

Offline Dan1195

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Re: element 117
« Reply #1 on: June 17, 2008, 02:43:09 PM »
Good question, I would have assumed 48Ca would allow for a higher cross-section due to its double magicity, besides the fact that combination you refer to leads to a compound system with 4 more neutrons. Only a couple reasons I could think of are 1) that they were unable to get enough 249Bk, which I would assume is in limited supply 2) They are looking at the viability of using projectiles heavier than 48Ca moving forward since using i48Ca on ever heavier actinide targets in not viable beyond element 118 due to the short lifetimes of heavier potential targets.

Offline gippgig

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Re: element 117
« Reply #2 on: July 16, 2009, 05:57:54 PM »
According to the Flerov Lab website (click on "Experiments" under "Research") the 249Bk + 48Ca reaction is currently scheduled (from July at least until the end of the year) at the U-400 cyclotron. We should soon have 117.

Offline Dan1195

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Re: element 117
« Reply #3 on: July 17, 2009, 03:28:11 PM »
Assuming (as expected) cross sections are similar to what was observed with 118..

Btw, recently I found a conference presentation where Dubna presented some results from the recent 270Hs experiment. http://www.np.ph.bham.ac.uk/IOP09/iop_talks/07_04_09_Parallel_2/07_04_09_Parallel_2.htm select Y. Tsyganov.ppt. Both the 270Hs and 266Sg daughter decay properties were confirmed and the half-life of 270Hs was actually measured (7.6 s) for the first time. The previous experiment was able to measure the alpha energy only.

Offline gippgig

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Re: element 117
« Reply #4 on: September 06, 2009, 08:56:12 PM »
See www.russiatoday.com/Sci_Tech/2009-07-01/New_chemical_element_to_be_synthesized_in_Russia.html?fullstory for a story on the preparation of the 249Bk target for this experiment.

Offline Dan1195

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Re: element 117
« Reply #5 on: September 08, 2009, 08:51:53 PM »
The 330 day half-life of 249Bk obviously limits the time within which the experiment can be run. Even with the 3-4 month window Dubna is using to perform the experiment, the half-life of the target is short enough that the chance the 48Ca fuses with the Beta decay product of this nucleus, 249Cf instead of the intended target is high enough that it cannot be dismissed out of hand. Perhaps the beam energy used (which might be slight different that the 118 experiments, I haven't looked at that) may reduce the likelihood of this enough so the chance is negligable.

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