Why Does Fission Chamber React to Neutron Fluxes Over Source Range?

In summary, the reason why a fission chamber would start to work from neutron fluxes more than source range is because the detector is more sensitive to neutrons.
  • #1
chivasorn
22
0
why does fission chamber start to work from neutron fluxes more than source range in spite of being a kind of ionization chamber that is sensitive to gamma rays?
 
Engineering news on Phys.org
  • #2
chivasorn said:
why does fission chamber start to work from neutron fluxes more than source range in spite of being a kind of ionization chamber that is sensitive to gamma rays?
Well, the purpose of a fission chamber is to measure neutron radiation (by virtue of induced fissions), and not gamma or beta radiation. If a detector measures the radiation fields of different types when one is interested in a specific type, the one has to have another detector sensitive to the type which one must exclude.

The goal of a fission chamber is to have it be more sensitive to neutrons than gamma or beta particles. One way would be to shield it with a thick high Z material (which would absorb betas (electrons) and scatter (absorb) gammas (by Compton and photoelectric effects), while having a low absorption cross-section for neutrons, such that it responds primarily to the neutron radiation. I believe such a detector also has a lower voltage than a gamma or beta detector.
 
  • #3
If you are talking about a LWR incore detector, there are 10 orders of magnitude more neutrons at full power than shut down. It would be hard to make a fission chamber detector capable of working over such a large range. That is why there are different kinds of detectors to use while at low power or shut down.
 
  • #4
Excore detectors possibly would be ion-chambers. In-core detectors are solid state.

http://www.freepatentsonline.com/3872311.pdf (1973)

http://www.freepatentsonline.com/4123658.pdf (1977)


In the power range, one has a large signal-to-noise ratio as compared to the source range where the signal-to-noise ratio is very low due to the low level of neutrons compared to gammas.

See also - V and Rh detectors are most common.
http://www.tpub.com/content/doe/h1013v2/css/h1013v2_75.htm
http://www.tpub.com/content/doe/h1013v2/css/h1013v2_76.htm (see discussion on wide range fission detectors)
 

1. Why is a fission chamber important in studying neutron fluxes?

A fission chamber is important because it is able to detect and measure the number of neutrons that are present in a given area. This is crucial in understanding the behavior and characteristics of nuclear reactions, as neutrons are key particles involved in fission reactions.

2. How does a fission chamber react to neutron fluxes over source range?

A fission chamber is designed to respond to neutron fluxes by producing an electric signal. When a neutron enters the chamber, it causes a fission reaction in the detector material, releasing charged particles that generate an electric current. The strength of this current is directly proportional to the number of neutrons present, allowing for accurate measurement of neutron fluxes.

3. What is the source range of a fission chamber?

The source range of a fission chamber refers to the range or distance from which it is able to detect and measure neutron fluxes. This can vary depending on the design and sensitivity of the chamber, but typically ranges from a few centimeters to several meters.

4. How does a fission chamber differ from other types of neutron detectors?

A fission chamber differs from other neutron detectors in that it relies on the fission reaction of the detector material to detect and measure neutron fluxes. Other detectors may use different methods such as capturing or scattering neutrons, but a fission chamber is specifically designed for fission reactions.

5. What are some applications of fission chambers in scientific research?

Fission chambers have a wide range of applications in scientific research, including nuclear physics, nuclear engineering, and nuclear medicine. They are commonly used in experiments to study the properties of nuclear reactions, monitor nuclear reactors, and measure radiation levels in medical imaging and cancer treatment.

Similar threads

FLUKA: Why Does Neutron Flux Increase When Passing Through a Moderator?
    • Nuclear Engineering
Replies
5
Views
838
Beryllium n:2n reactor fuel
    • Nuclear Engineering
Replies
3
Views
1K
Can Someone Explain How Nuclear Fuel Rods Heat Water in a Reactor?
    • Nuclear Engineering
Replies
10
Views
2K
Radiation effects/damage in structural alloys and ceramics
    • Nuclear Engineering
Replies
2
Views
765
How does D-T fusion reaction utilize its waste to create more fuel?
    • Nuclear Engineering
Replies
3
Views
1K
Clean lithium fission saltwater rocket
    • Nuclear Engineering
2
Replies
46
Views
12K
Who Would Benefit from a Comprehensive Database of Cumulative Fission Yields?
    • Nuclear Engineering
Replies
2
Views
2K
Prompt neutrons, delayed neutrons, chain reaction control
    • Nuclear Engineering
2
Replies
36
Views
5K
I Concentrated arcs in bubble chamber photos
    • High Energy, Nuclear, Particle Physics
Replies
2
Views
1K
Danger and risks of fusion power
    • Nuclear Engineering
Replies
7
Views
2K

Hot Threads

Recent Insights

Back
Top