Beamstop with Integrated X-ray Diode Sensor


The MC group developed a versatile beamstop with an integrated PIN diode sensor using non-specialized components (Fig. 1). The miniature PIN diode is molded into a tungsten epoxy composite cup with a total diameter of 1.5 mm. The cup is supported on a thin fiberglass arm with printed circuit traces to transmit the diode signal. The assembly has an active area of approximately 100 μm in diameter. As the diode is encapsulated in plastic, the response diminishes with decreasing energy but is still useful at 6 keV.

Figure 1. Integrated Diode Beamstop. Click-on to enlarge.


  1. Beamstop with integrated x-ray sensor
    Ellis, P.J.; Cohen, A.E.; Soltis, S.M. J Synchrotron Radiat 10, 287-288 (2003).


Item Vendor Part Number Notes
Bob Smith Industries BSI-205 Clear Slow Epoxy Amazon BSI-205 Strongly Recommended. Many other brands of epoxy use fillers which are not good insulators.
Sensor Pin Diode Mouser Electronics Phillips BAP64-02

Fabrication and Assembly

Fabrication and assembly instructions are described in the Reference Publication.

Supplemental photos for molding the tungsten cup are shown below: 

Figure 2. Overview of the mold. Click-on to enlarge.

Figure 3. Close-up of the mold and plunger. Click-on to enlarge.

Figure 4. Close-up of the beamstop inside the mold.

Figure 5. Beamstop removed from mold - before trimming excess epoxy. Click-on to enlarge.