Buying an He3 detector from an official supplier

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Kuba Anglin
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Buying an He3 detector from an official supplier

Post by Kuba Anglin » Thu Oct 05, 2017 1:10 am

I'm in the process of transferring my reactor to a lab space at my university to start a plasma physics research group. The professor helping me has tasked me with finding a neutron detector capable of high accuracy readings from an official manufacturer (not eBay). Costs will be covered by my university.

The Radiation Safety Committee has strict rules regarding neutron-generating devices, and I need to verify that my device is safe to operate when the correct procedures are followed. Can anyone recommend where I can find such a detector? I also need metering equipment and power amps from these "official" manufacturers to satisfy the safety department.

Ludlum sells detectors and metering equipment, but I can't find any amplifiers on their site.

Thanks,
Kuba

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Richard Hull
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Re: Buying an He3 detector from an official supplier

Post by Richard Hull » Thu Oct 05, 2017 4:06 am

You will need a calibrated all in one meter detector to satisfy your rad-safe CHP. Most manufacturers do not make or sell a highly sensitive neutron detector. They are typically assembled and calibrated by end user's. Ludlum should sell a matched counter and bonner sphere which is a calibrated system, but not very sensitive to low level neutron flux. Most folks making neutron detction gear are making them for the nuclear power industry where significant neutron radiation is to be looked for.

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Re: Buying an He3 detector from an official supplier

Post by Andrew Seltzman » Thu Oct 05, 2017 4:35 am

Would they be satisfied with a BTI-PND dosimeter? They are calibrated and directly read dose in real time.
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Kuba Anglin
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Re: Buying an He3 detector from an official supplier

Post by Kuba Anglin » Thu Oct 05, 2017 6:20 am

The professor aiding me, Dr. George S. Brown, used to chair the Radiation Safety Committee. He stated that he understands my project is not particularly dangerous with respect to radiation. However, if a visitor were to wander by the physics department and contract a headache (knowing that my reactor was nearby), they could potentially sue the school. I need to be absolutely certain the reactor is not irradiating nearby classrooms.

Professor Brown suggested that I configure the detector so that an abnormally high neutron flux will kill the power supply immediately. This is not for any practical purpose, it's just to impress the committee. This operation cannot be accomplished by a bubble dosimeter.

I think the Ludlum all-in-one models are the way to go. Perhaps this model: http://ludlums.com/component/virtuemart ... temid=2657

At 30 cpm per mrem/hr, the detector should be able to provide evidence of neutrons (around 75 cpm for an isotropic flux of 50k n/s). The digital output will enable automatic HV shutoff. I just sent a quote request.

Kuba

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Richard Hull
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Re: Buying an He3 detector from an official supplier

Post by Richard Hull » Thu Oct 05, 2017 2:58 pm

A fusor would have to be working at a pretty high order of efficiency to produce just 2 mrem per hour at point contact with the device. This is rare for first pass operation.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Kuba Anglin
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Re: Buying an He3 detector from an official supplier

Post by Kuba Anglin » Thu Oct 05, 2017 6:33 pm

Perhaps that would be for the best. If the detector shows that there is little to no neutron radiation, the safety team should have few reasons to disallow my reactor. I can continue using bubble dosimeters for my experiments while running the Ludlum in order to satisfy the safety team.

I plan on improving my reactor, so the Ludlum detector should be of more practical use later on when I am generating higher neutron fluxes.

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Dennis P Brown
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Re: Buying an He3 detector from an official supplier

Post by Dennis P Brown » Fri Oct 06, 2017 11:46 am

I might have missed this in your post but have you directly discussed this with the safety person, yet? They may ask you for guidance on some aspects (like possible x-ray danger, as well) but they should be able to decide exactly what is required rather than us speculating here. For example, explain what the maximum possible neutron generation rate could be (an estimate using best average results here) and how you will measure your actual radiation level. Maybe provide the detector/shut down system you mentioned. They may or may not be interested in shielding and/or this alone might be enough along with a validation measurement. Again, speculation here but they could give exact requirements, maybe?

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