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Development of a photodiode measuring system for the time-resolved measurement of pulsed and continuous X-rays


The newly developed radiation pulse measuring system is equipped with just one detector but is capable of measuring radiation pulses across a broad range of pulse durations and intensities. It is able to plot intensity and dose rates with a time resolution of a few ns and allows dose rate measurements ranging from just a few mGy/h in continuous radiation fields to several MGy/h in pulsed fields.

Pulsed radiation fields are used in many different disciplines, systems and installations, including, for example, in particle accelerators used for research or in the field of medical X‑ray diagnostics. Here, large differences of several orders of magnitude are seen in both the dose rate and the time distribution of the pulses. To allow dose rate measurements with high time resolution and simultaneous signal conditioning to be carried out under these different radiation conditions, the possibility of switching electronically between different measurement modes was realized within a single measuring instrument. Figure 2 shows the frequency bands in which the instrument can be operated as well as the possible dose rates. This system is particularly adept at taking measurements of short pulses with higher pulse dose rates, but it can also be deployed in continuous radiation fields having a sufficient dose rate. This application is particularly beneficial in association with so‑called counting and spectrometric systems, which at high dose rates suffer dead‑time and pile‑up effects. Since the measuring ranges to a great extent also correspond to the system parameters of the reference radiation fields at Department 6.3, it was possible to carry out initial measurements here. The electronic behavior of the different modes has been characterized and traced using optical methods with a 300 µm silicon PIN photodiode serving as the sensor.

For applications in unknown radiation fields, the measuring process is therefore greatly simplified by the possibility of switching easily between the different measuring modes.

This work was carried out as part of a bachelor's thesis in collaboration with the Ostfalia University of Applied Sciences in Wolfenbüttel.

Fig. 1:   Measurement setup with electronic measuring system and oscilloscope


Fig. 2:   Frequency and intensity ranges for the different switching modes, time resolution ta ≈0.35/fg


Opens local program for sending emailJ. Koll, Department 6.3, Working Group 6.35

Opens local program for sending emailJ. Roth, Department 6.3, Working Group 6.35