What causes secondary photons in He-3 detectors?

[Neutroniclad]

Does all the signals detected by He-3 detector caused by neutrons?
When the He(n,p)t reaction occurs, will proton cause any secondary x-ray photons since it de-accelerates in matter.

 

[Astronuc]

When the He(n,p)t reaction occurs, will proton cause any secondary x-ray photons since it de-accelerates in matter.

Think about the ionization energies of hydrogen (13.6 eV) and helium (1st 24.6 eV, 2nd 54.4 eV) so they will be UV or very soft X-rays, which would not ionize He atoms. Look at the emission or line spectra of H and He.

The combined energy of the p and t is the Q-value, 764 keV, with 573 keV to the proton and 191 keV to the triton). When they neutralize, the photons from them (t,p) are quite low in energy. More energetic gamma-rays and X-rays can originate in the metal wall or anode of the detector, if the t or p hit the anode or wall, and of course, they can originate from outside the detector.

Neutron detectors, including He-3: http://web.mit.edu/8.13/www/JLExperiments/38/tgm-neutron-detectors.pdf

Read up on gas-filled proportional counters and their sensitivity, or insensitivity, to X-rays and gamma-rays.

http://www.lanl.gov/orgs/n/n1/panda/00326408.pdf
http://large.stanford.edu/courses/2012/ph241/lam1/
https://www.gemeasurement.com/radia...etectors/helium-3-filled-proportional-counter
http://www.ncnr.nist.gov/staff/hammouda/distance_learning/chapter_13.pdf
http://www.whoi.edu/fileserver.do?id=166724&pt=2&p=155629

http://arxiv.org/pdf/1212.4724.pdf

Gamma-ray detectors - http://www.lanl.gov/orgs/n/n1/panda/00326398.pdf
http://www.canberra.com/literature/fundamental-principles/pdf/Gamma-Xray-Detection.pdf