DeepBlueMarin 04222013
Irradiation of Silver coins from Deep Blue Marin performed on April 22, 2013
Large Coin
Large Coin mass =6.8921 g
Medium Coin mass =4.628 g
Small coin mass= 6.9325 g
Raw Spectrum
Calibration
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| 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
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 |
Rate normalized spectrum
Missing Peaks
All three coins were irradiated for 1 hour on 4/22/2013 starting at 11:19 am.
The photon spectrum was measured separately for each coin 5 hours after the activation.
The Large coin spectrum was measured on 4/22/2013 from 17:07:34 until 17:19:17. (livetime = 657.476 second)
The Medium coin on the same day 4/22/2013 from 17:20:50 until 17:37:18. (livetime = 298.611 second)
The small coin on the same day from 17:38 until 17:53:09. (lifetime = 823.458)
388 keV line
A 657 second measurement at 17:07 on 4/22/2013 (irradiation was done from 11:19 until 12:19 the same day)
The Large coin has a line at 388 keV but the small or medium does not.
A 141453 second measurement performed 19 days later on 5/11/2013.
Possible Isotope that produce this line are
Ce-135(17.7 hr) ,Sr-87m(2.8 hr), Y-87(79.8 hr), Hg-195m (41.6 hr)
1365 keV line ?
The Large coin has a line at 1365 keV but the small or medium does not.
Possible Isotope that produce this line are
Os-179
Relative to Nickel
Experimental Setup
Nickel counts
Nickel (1) It was in front of the stack. It was counted on April 22,2013. Counting started at 16:53:44 and stopped at 17:04:41.
Nickel (2) It was in the back of the stack. It was counted on April 22,2013. Counting started at 16:41:30 and stopped at 16:52:43.
he measurement was done in position K. The gamma line used for measurement was 1378 KeV and corresponding detector efficiency for this energy and position was 0.0003227 .The half live of Ni-57 is 36 hours.
Ni(1) 0.153 grams, 2.949 uCi
Ni(2) 0.161 g 2.582 uCi
Detection Limits
Y = total count
= concentraion
= standard deviaiton