Naslov
Single-layer Compton detectors for measurement of polarization correlations of annihilation quanta

Autori
Makek, Mihael ; Bosnar, Damir ; Pavelić, Luka ; Šenjug, Pavla ; Žugec, Petar

Izvornik
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment (0168-9002) 958 (2020); 162835, 4

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Gamma-ray polarization ; Positron Emission Tomography ; Compton imaging

Sažetak
Measurement of gamma-ray polarization can provide valuable insight in different areas of physics research. One possible application is in Positron Emission Tomography, where the annihilation quanta with orthogonal polarizations are emitted. Since polarization can be measured via Compton scattering, the initial orthogonality of polarizations can be translated to correlation of azimuthal scattering angles, and this correlation may be exploited as an additional handle to identify the true coincidence events. In order to examine the concept of utilizing the polarization correlations in PET, we have used a system of two compact, position and energysensitive Compton scattering detectors in coincidence mode. Each consists of a single matrix of scintillation pixels, read-out by a matching array of Silicon photomultipliers on the back side. The Compton events in each module are clearly identified and the scattering angles are econstructed from the energy deposition and event topology. We have extracted the polarimetric modulation factors from the measured azimuthal scattering angles of the two Compton-scattered gammas and studied their dependence on Compton scattering angles 𝜃 and on azimuthal resolution 𝛥𝜙. For scattering angles around 𝜃1, 2 = 82◦, where the maximum modulation is expected, the modulation factors from 𝜇 = 0.15±0.01 to 𝜇 = 0.27±0.02 have been measured, depending on the azimuthal resolution, which is governed by event topology in the detectors. Analogously, for scattering around 𝜃1, 2 = 70◦, modulation factors from 𝜇 = 0.12±0.01 to 𝜇 = 0.21±0.02 have been obtained. The results show that the measurement of the polarization correlations of annihilation quanta are feasible with compact single-layer, single-side read-out detectors, which may be used to build cost- efficient systems for various applications where gamma-ray polarization information is of interest.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Interdisciplinarne prirodne znanosti

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