DeepBlueMarine Physics

Ancient Silver

File:Meyers Zelst Sayre BNL-21513.pdf This paper suggest that the gold and iridium content can be used to distinguish between Sasanian (Iran) coins and other silver coins.

Activating gold

Neutron knock out

[math]{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 or the rest of the time it Beta decay to Hg-196

The highest relative intensity gamma ray has an energy of 333.03 keV after Au-196 undergoes electron capture. Pt-196 is stable.

If Pt-196 is in an excited state, then there are two lifetimes to de-excite of 8.1 seconds and 9.6 hours . For the 9.6 hours state then dominant intensities are a photon emission energies of 188.27 and 147.81 keV.

Proton Knockout

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

Pt-196 is naturally occurring in 25% of the Platinum

You will need to produce it in an excited state (356, 689, 877,1526 keV) in order to get a gamma.

Activation Iridium

There are two naturally occuring isotopes of Iridium (37% Ir-191, 63%Ir-193)

Neutron knock out

[math]{191 \atop\; }Ir (\gamma,n){190 \atop \; }Ir[/math]

After 11.78 days Ir-190 electron captures to Os-190 (dominant decay) with the most intense line emission of 186.68 keV.

Proton knock out

[math]{191 \atop\; }Ir (\gamma,n){190 \atop \; }Os[/math]

[math]{193 \atop\; }Ir (\gamma,n){192 \atop \; }Os[/math]

Osmium 192 and 190 are stable.

Coincidence PAA

The NAA analysis suggests that Gold and Iridium are useful for distinguishing between silver coins

Gold CPAA

Both neutron and proton knockout to Platinun-196

[math]{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. 24.7% of the time it decays to the next higher energy 2+ state of Pt-196 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.

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

Pt-196 is naturally occurring in 25% of Platinum.

PAA_Research