Difference between revisions of "Project:Subatomic metrology"

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Latest revision as of 15:29, 3 June 2013


A project to acquire the necessary apparatus and knowledge to allow for the meaningful study radioactivity and subatomic particles in general.

Starting equipment

One of the main standards in electronic equipment intended for study of nuclear phenomena is the NIM or nuclear instrumentation module. These are basically a slender box with a standard power connector on the rear which slots into a chassis known as a NIM bin or creat in a maner similar to server blades in a blade chassis. There is a vast array of NIMs available to perform numerous electronic functions from the very specific to the quite generic. The advantage of this system are twofold; First, extreme flexibility it afforded by it's modular nature. Secondly this is an old standard that has been in use for a long time and as such NIMs often come up on ebay for not too hideous prices. Though some of these may be quite old, they are usually made to extremely high standards with very high quality components, making repair a worthwhile option.

NIM bins would commonly consume about 6U in a 19" rack, however I have a slightly smaller one, capable of housing 7 single width NIMs which should be enough to get us started and not consume more space than necessary. I also have a basic set of NIMs with which to populate it, a HV PSU, a counter/timer, signal amplifier and rate meter. The bin i will donate to the space, my NIMs at this stage i am providing on the basis of a 'semi-permanent loan' (basicaly until I leave London)

I will also be providing a somewhat decrepit NaI:Tl scintillation counter and a thin window GM tube

Equipment required:

A wishlist most important first

  • The main thing we are lacking is a multichannel analyser, this is an apparatus that digitizes pulses generated by a detector and presents them as a histogram of pulse height (and therefore radiation energy) against number of pulses received thus generating a spectra of the energy of radiation incident upon the detector. I intend to make one but it is going to take some time.
  • A better scintilator would be nice, my chunk of NaI is going cloudy ;(
  • Lead! lots of lead. Background radiation is everywhere and really gets in the way when trying to get a spectra for low activity items, Lead several inches of lead shielding around the detector and item under study prevents this.
  • More NIMs are always good... you can't have too many!
  • Any CAMAC kit. (CAMAC is a newer version of NIM with a digital backplane. would be nice play with!)
  • photomultipliers, ion chambers, Helium-3 or BF3 proportional tubes (yeah, I live in hope) an HPGE detector (again... living in hope.. maybe we could cool it with a massive stack of peltiers...) CdTe semiconductor detectors, BGO scintilator, Lanthanum Chloride scintilator..... you get the idea ;)

Proposed uses:

  • Investigation of radioactivity in common and uncommon items
  • Determination of radionuclide content items by analysis of decay (e.g chunks of rock)
  • Investigation of novel detector materials, growing of scintillation crystals, novel semiconductor detectors
  • Investigation of anthropogenic background radiation and cosmic background.

Training required:

Due to the complexity and flexibility of the NIM system, some training will be required to enable proper operation. High voltages are required for many of the sensors involved. The thin window GM tube is *extremely* fragile and somewhat irreplaceable so *please* be carefull with it.