Bicron 1XMP.040B is a low-energy gamma (e.g. x-ray) NaI(Tl) detector similar to FIDLER, except that it is much smaller in size. The scintillator crystal dimensions are 1″ by 1 mm, and the detector cross-section is shown on Fig. 1.

Bicron 1XMP.040B model (Fig. 2) comes with a collimator for improved x-ray detection directionality and requires a power supply (such as Ortec 115, Fig. 3) to provide power for it’s preamp.

Using MCA-PRO 16 and PulseCounter software I have captured ¹³⁷Cs, ⁵⁷Co, ¹³³Ba, and ⁵⁵Fe spectra – Fig. 4-6. Detector bias was set to 550V and thanks to the preamp the signal range was positive 0 to 2V. The spectra appeared normal and I had no problems resolving ⁵⁵Fe peak.

Compared to FIDLER the counts were significantly lower due to smaller detector size, which was further restricted by collimator. The collimator blocked x-rays very effectively and I was getting virtually no counts unless I placed my sources directly on the line of sight defined by the collimator slot.

Bicron 1XMP.40B is a good choice when one has to register x-rays arriving from a well-defined point source. And it is not going to break your bank!