Search found 56 matches

by pietkuip
07 Jun 2015, 19:01
Forum: Spectrum
Topic: Coincident spectra from Compton scattering Cs-137
Replies: 18
Views: 9490

Re: Coincident spectra from Compton scattering Cs-137

Steven, the peaks in the spectra from the plastic scintillator are not photopeaks. They are parts of the Compton continuum, which is a continuum because normally one sees contributions from all angles. Imposing a coincidence condition for a certain range of angles (defined by sized and distances) ma...
by pietkuip
07 Jun 2015, 03:33
Forum: General discussion
Topic: Cosmic radiation
Replies: 15
Views: 8740

Cosmic radiation

I would sometimes see or hear giant pulses, way off the scale. I had kind of assumed that these were artifacts from the PMT or something. But now I know: they are atmospheric muons, with typical energies of 4 GeV. I looked at them with the coincidence setup that Tom Andersson described yesterday. I ...
by pietkuip
06 Jun 2015, 18:35
Forum: Spectrum
Topic: XRF Gold Assay Experiment
Replies: 16
Views: 8840

Re: XRF Gold Assay Experiment

I would not use an alpha emitter, unless it is the top few micrometers that one is interested in. Gamma (and beta) would make the setup sensitive to bulk composition. Licensing is usually less of a problem than for radioisotopes. Everybody used to have x-ray sources: the CRT tv-sets and computer mon...
by pietkuip
06 Jun 2015, 17:22
Forum: Spectrum
Topic: XRF Gold Assay Experiment
Replies: 16
Views: 8840

Re: XRF Gold Assay Experiment

Knowing your setup, maybe I could fool you with gold-plated lead :) Because I would guess that the gold K fluorescence is induced by alpha particles from the americium (PIXE). The alphas do not penetrate, so a thin surface layer gives the same intensity. Also: the gold will scatter 60 keV from the s...
by pietkuip
06 Jun 2015, 16:41
Forum: Spectrum
Topic: Coincident spectra from Compton scattering Cs-137
Replies: 18
Views: 9490

Re: Coincident spectra from Compton scattering Cs-137

Beautiful data! I hade never done this before, estimated the chance that it would work to 50 % or so, but Tom was eager to try. I suggested to try first with the detectors really close to each other, and this gave immediately coincident spectra with good statistics. So then Tom increased distances f...
by pietkuip
26 May 2015, 08:04
Forum: Spectrum
Topic: Manganese 56
Replies: 10
Views: 5267

Re: Manganese 56

That is impressive. I would love to play with something like that.

I have no intuition for that kind of fast neutron fluxes, but I wonder about the levels where one needs to start worrying about damage to electronics. But maybe the electronics was not strapped on when the source was running?
by pietkuip
26 May 2015, 06:25
Forum: Spectrum
Topic: Manganese 56
Replies: 10
Views: 5267

Re: Manganese 56

That is several orders of magnitude more neutrons than what I have! I am interested in the details. It is easy to reduce the neutron energy: just use a centimeter or so of water or something else with a lot of hydrogen (candle, tealight) as a moderator. This is what our source looks like . The sampl...
by pietkuip
25 May 2015, 22:36
Forum: Spectrum
Topic: Manganese 56
Replies: 10
Views: 5267

Re: Manganese 56

You might get higher activity if you use thermal neutrons from a moderator. I do this experiment in the course lab with our weak neutron source (3 mCi radium mixed with beryllium). My estimate of the flux is 80 neutrons per cm^2 per second. With an AA battery as a sample, typical results look like t...
by pietkuip
25 May 2015, 21:39
Forum: Spectrum
Topic: Tritium spectrum
Replies: 3
Views: 3275

Re: Tritium spectrum

I put one of these Gaseous Tritium Light Sources in front of our Amptek silicon detector over the weekend. It has better resolution. Most of the spectrum is Bremsstrahlung, but there are also two clear peaks. Those are the characteristic emission lines of zinc. The Ka peak is more attenuated by the ...
by pietkuip
22 May 2015, 06:52
Forum: Resources
Topic: Indium 115 Spectrum - Gran Sasso Experiment
Replies: 1
Views: 4597

Re: Indium 115 Spectrum - Gran Sasso Experiment

"intensive irremovable background" In our course lab the students do experiments on indium every year, but I never knew it was not quite stable. It is excellent for neutron activation experiments: large cross section and the product In-116 has a suitable half-life of about one hour, decaying with di...