- The main problem with measuring neutrons is that they are uncharged
and do not directly excite ionization in the matter through which they
are travelling.
- They are detected by nuclear reactions which produce charged
particles. These particles are collected and processed.
- The concern here, using gas detectors, is with slow neutrons, i.e.
those with energies below the cadmium cut off (~ 0.5 eV)
Commonly used detectors are:
The BF3 (boron
trifluoride) detector
Boron lined detectors
3He detectors
Fission counters |
Nuclear reactions used in neutron detection
| Target |
reaction |
Product |
Q(MeV) |
Thermal sn |
| 3He |
n,p |
3H |
0.764 |
5330 |
| 6Li |
n,a |
3H |
4.780 |
940 |
| 10B |
n,a |
7Li |
2.792 |
6% of 3840 |
| 10B |
n,a |
7Li |
2.310 |
94% of 3840 |
| 235U |
n,f |
f.f. |
~200 |
582 |
| 238U |
n,f |
f.f. |
~200 |
(En > 1 MeV) |
|
