Characterization of a cylindrical plastic β-detector with Monte Carlo simulations of optical photons

Abstract

In this work we report on the Monte Carlo study performed to understand and reproduce experimental measurements of a new plastic β-detector with cylindrical geometry. Since energy deposition simulations differ from the experimental measurements for such a geometry, we show how the simulation of production and transport of optical photons does allow one to obtain the shapes of the experimental spectra. Moreover, taking into account the computational effort associated with this kind of simulation, we develop a method to convert the simulations of energy deposited into light collected, depending only on the interaction point in the detector. This method represents a useful solution when extensive simulations have to be done, as in the case of the calculation of the response function of the spectrometer in a total absorption γ-ray spectroscopy analysis.

Experimental study of Tc100 β decay with total absorption γ -ray spectroscopy

“…Accordingly, after the purification in the JYFLTRAP double Penning trap [42], the activity was implanted directly at the bottom of a plastic β detector, which has a vase-shaped geometry [43]. This detector was placed at the center of the DTAS detector system.…”

“…3. For this purpose we used a vase-shaped plastic detector [43] of 35 mm external diameter and 50 mm length with 3 mm thickness in the lateral walls and in the bottom. The plastic detector was covered internally by a thin aluminized-mylar reflector in order to improve the light collection.…”

“…4. Due to the geometry of this detector, a careful characterization with MC simulations using optical photons was needed in order to understand and reproduce the shape of the resulting β spectra and calculate accurately the dependence of the β efficiency as a function of the β endpoint energy [43]. The amount of light collected from the lateral walls was shown to be less than the light collected from the bottom, thus producing the bump at the beginning of the spectrum shown in Fig.…”

“…Two different energy thresholds were identified depending on the point where energy is deposited in the detector: 30 keV for the bottom and 100 keV for the lateral walls (see Ref. [43] for more details).…”

Determination of β -decay ground state feeding of nuclei of importance for reactor applications

“…As described in Ref. [60] a different β detector was employed in this measurement, which consists of a vase-shaped thin plastic scintillator with close-to-4π solid angle coverage. The value of I 0 β obtained with the TAGS technique is compatible with the previous value from HR measurements (see Ref.…”