You are looking for something similar to https://en.wikipedia.org/wiki/Optoelectric_nuclear_battery https://en.wikipedia.org/wiki/Optoelectric_nuclear_battery o

You are looking for something similar to https://en.wikipedia.org/wiki/Optoelectric_nuclear_battery https://en.wikipedia.org/wiki/Optoelectric_nuclear_battery or another https://en.wikipedia.org/wiki/Betavoltaic_device https://en.wikipedia.org/wiki/Betavoltaic_device however these don't operate on gamma rays directly but work is ongoing https://iopscience.iop.org/article/10.1088/0268-1242/23/8/085001 https://iopscience.iop.org/article/10.1088/0268-1242/23/8/08...