DeepBlueMarin 04222013

Irradiation of Silver coins from Deep Blue Marin performed on April 22, 2013

Large Coin

Raw Spectrum

Calibration

Linear fit using several sources	Zoom in to the most intense line	The most intense line seems to be from positron annihilation

Energy Calibrated spectrum

Peak Ratios

Ratio of 511 and

Silver lines

Coin Size	511/451 ratio	511/748 ratio	511/1046 ratio
Large	87740/6639 =13.2	87740/2962=29.6	87740/2803 = 31.3
Medium	31950/2938 =10.9	31950/1239 =25.8	31950/1283=24.9
Small	87090/8184=10.6	87090/3790 =22.98	87090/3578=24.34

Gold lines

Consider the neutron knock out reaction on Gold

[math]\displaystyle{ {197 \atop\; }Au (\gamma,n){196 \atop \; }Au }[/math]

Au-196 decays with a half life 6.183 days of by electron capture to Platinum (Pt-196) 92% of the time.

There are two dominant photon energies of 333.03 keV and 355.73 keV. 67% of the time Au-196 goes to the 2+ excited state of Pt-196 after 34.15 ps . 24.7% of the time it decays to the next higher energy 2+ state of Pt-196 after 33.8 ps and then proceeds to emitt a 333.03 keV photon as it transitions to the lower 2+ state where it will emitt a 355.73 keV photon on its way to the ground state.

The spectra below show a clear peak at a photon energy of 356 keV but the signal at 333 keV is less convincing. The peak fit near the 333 keV energy has a Guassian mean of 332. Perhaps there are two different photon energies in the 33 keV region, one at 332 and the other at 333.5.

Coin Size	333 keV	356 keV	333/356 ratio
Large			5397/3672=1.47
Medium			2062/1432=1.44
Small			5552/3956 =1.40

Missing Peaks

388 keV line

The Large coin has a line at 388 keV but the small or medium does not.

PAA_DeepBlueMarine