Peter,

A Continuous Air Monitor (CAM) detector is a bit different than the PIPS used for Alpha spec counting in that they have to operate in an air flow that can be pretty rough, humidity, corrosive atmospheres, etc so they are ruggedized by having an thin aluminum surface and a varnish over it to protect the silicon which also to prevents light from reaching it. A standard PIPS has none of this as it operates in vacuum chamber.?

The broadening of the FWHM with distance is due to the angular ray path but for a CAM that distance is fixed so you will be stuck with that FWHM. Varying the distance between the detector and source will, as you say, change the energy due to interactions with the air molecules. It will be seen as a long low energy tail from the peak energy and with increased distance a shift and broadening in the energy peak to lower energy.

Dud KK7IF

?

?

Hi:
Please excuse my lack of knowledge. I am new to alpha spectrometry.?
Not having a selection of alpha check sources I was wondering if varying the distance between a detector and a check source would change the measured energy ? I made the assumption that the alpha particle would loose energy? through interactions with air during its travel to the detector. Another assumption I had was that interactions would broaden the measured FWHM of the measured peak? BTW I have an Eberline Alpha 6A-opt1, which? I believe has a??Quantrad 500-PNC-BNC-Alum 1" sensor,?but I can't find its specifications.?

I stumbled across and article:?? and inside figure 6 caught my eye. It seems that due to the detector construction of a PIPS, the closer the detector is to a source, the wider the fwhm gets. Would that also apply to the detector in the Alpha 6A-opt1?

p

No the Alpha 6a looks at alpha spec you can even get a uranium Eprom for it

https://chpconsultants.com/collection/alpha-6a-eprom-for-monitoring-radon-a4-v1-0-2/

Dud

?

?

Dud:
?thanks for the reply. I wasn't sure because the Eberline Alpha 6A ( not -opt1) with the same sensor has a 8 bit resolution for the energy peaks, so I was led to believe that it could detect the energy of an alpha particle.?
So infact the detector used in the Alpha 6A-opt1? can not resolve the energy of an alpha particle.
Would you happen to have the specs for the??Quantrad 500-PNC-BNC-Alum 1" sensor?

P