icon Kapiti gaigakaunta

Kapiti, New Zealand

icon guff

19 March 2011
This is a scintillation detector sitting on a workbench on the Kapiti coast north of Wellington, New Zealand.
It consists of an NaI(Tl) (Thallium doped Sodium Iodide) crystal, I kid you not, under a tinfoil hat. When ionising radiation hits the crystal, scintillation, flashes of light, happens. The crystal peak emission wavelength is 430nm ("super blue").
This is faced up against a photomultiplier tube to complete the detector.
A power supply and interface came with the detector. This runs on 24VDC and generates the high voltage for the photomultiplier. The various electrodes in the photomultiplier tube are connected to a resistive divider in the power supply. A BNC connector carries the electrical output pulses.
These pulses are tee-ed off to a sound card line in, which is used for spectrographic analysis, and to a buffer and an RS232 driver which is used to make the Counts Per Minute graphs.
This all makes a highly sensitive, somewhat unstable, γ (gamma) ray detector capable of broadband spectrographic operation, with peak sensitivity around 210 keV.
Gamma rays have energies of 124 keV or more.
Uncalibrated and subject to change.
Kia kaha Christchurch.
Kia kaha Japan.
Kia kaha katoa.

icon index

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