Sensitivity of Discrete Symmetry Tests in the Positronium System with the J-PET Detector

Gajos, A.

doi:10.3390/sym12081268

Cited by 9 publications

(14 citation statements)

References 51 publications

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“…The definition of the annihilation plane orientation through the two most energetic photons is merely a convenient convention and thus does not impose a bias on the space of kinematical configurations of three-photon annihilations, a problem affecting other conceivable angular correlations for o-Ps → 3γ events. Consequently, the choice of this observable for the CPT test minimises spurious asymmetries originating from the detector geometry that could mimic a violation 26 . Moreover, due to the neutrality of the final state of the o-Ps → 3γ process, radiative corrections that could cause fake CPT asymmetry, thus posing a natural limit on the sensitivity of such a test, are only expected at a precision level of 10 − 9 20,23 , thus leaving significant exploratory potential.…”

Section: Resultsmentioning

confidence: 99%

Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

et al. 2021

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Section: Resultsmentioning

confidence: 99%

Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

et al. 2021

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“…This will be further augmented by a new design of the annihilation chamber with spherical geometry, increasing the o-Ps formation probability by a factor of approximately 1.5 with a given β + source activity and minimising potential spurious asymmetries from the geometry of the experimental setup [23]. These…”

Section: Conclusion and Prospectsmentioning

confidence: 99%

“…The definition of the annihilation plane orientation through the two most energetic photons is merely a convenient convention and thus does not impose a bias on the space of kinematical configurations of three-photon annihilations, a problem affecting other conceivable angular correlations for o-Ps→ 3γ events. Consequently, the choice of this observable for the CPT test minimises spurious asymmetries originating from the detector geometry that could mimic a violation [23]. Moreover, due to the neutrality of the final state of the o-Ps→3γ process, radiative corrections that could cause fake CPT asymmetry, thus posing a natural limit on the sensitivity of such a test, are only expected at a precision level of 10 −9 [17,20], thus leaving significant exploratory potential.…”

Section: Cpt-prohibited Angular Correlations In Ortho-positronium Annmentioning

confidence: 99%

“…the J-PET detection setup. Providing up to quadruple enhancement in registration probability for a single annihilation photon, it can increase the overall detection efficiency of o-Ps→3γ events by a factor of 64.This will be further augmented by a new design of the annihilation chamber with spherical geometry, increasing the o-Ps formation probability by a factor of approximately 1.5 with a given β + source activity and minimising potential spurious asymmetries from the geometry of the experimental setup[23]. These improvements will allow the J-PET setup to collect a dataset of exclusively recorded ortho-positronium three-photon annihilations of unprecedented size.…”

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confidence: 99%

“…Moreover, the control over systematic effects in the presented measurement and coverage of a broad span of kinematic configurations of recorded events. This eliminates false asymmetries from the detector geometry, and opens the way to exploring angular correlation operators for which usage was not feasible in previous experiments, such as the S • k 1 correlation, which is odd under both CP and CPT transformations[23].Ministry for Science and Higher Education through grant nos. 6673/IA/SP/2016 and 7150/E-338/SPUB/2017/1; and the Austrian Science Fund FWF-P26783.1911.12059.…”

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Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

Moskal

Gajos

Mohammed

et al. 2021

Preprint

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Charged lepton system symmetry under combined charge, parity, and time-reversal transformation (CPT) remains scarcely tested. Despite stringent quantum-electrodynamic limits, discrepancies in predictions for the electron–positron bound state (positronium atom) motivate further investigation, including fundamental symmetry tests. While CPT noninvariance effects could be manifested in non-vanishing angular correlations between final-state photons and spin of annihilating positronium, measurements were previously limited by knowledge of the latter. Here, we demonstrate tomographic reconstruction techniques applied to three-photon annihilations of ortho-positronium atoms to estimate their spin polarisation without magnetic field or polarised positronium source. We use a plastic-scintillator-based positron-emission-tomography scanner as a high-acceptance photon detector to study CPT-prohibited angular correlation in ortho-positronium (o-Ps) annihilations. We record an unprecedented range of kinematical configurations of o-Ps annihilations into three photons. Tomographic reconstruction of the annihilation points in a large medium allows single-event estimation of positronium spin orientation and, consequently, determination of the complete spectrum of angular correlation between the annihilation plane orientation and positronium spin, the non-vanishing expectation value of which would manifest CPT-violating effects. We find no violation at the precision level of 10^{−4}, with a fourfold improvement on the previous measurement. This work enables application of positronium-imaging techniques to study discrete symmetries in positronium decays.

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Simulating NEMA characteristics of the modular total-body J-PET scanner—an economic total-body PET from plastic scintillators

et al. 2021

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The purpose of the presented research is estimation of the performance characteristics of the economic total-body Jagiellonian-PET system (TB-J-PET) constructed from plastic scintillators. The characteristics are estimated according to the NEMA NU-2-2018 standards utilizing the GATE package. The simulated detector consists of 24 modules, each built out of 32 plastic scintillator strips (each with cross section of 6 mm times 30 mm and length of 140 or 200 cm) arranged in two layers in regular 24-sided polygon circumscribing a circle with the diameter of 78.6 cm. For the TB-J-PET with an axial field-of-view (AFOV) of 200 cm, a spatial resolutions (SRs) of 3.7 mm (transversal) and 4.9 mm (axial) are achieved. The noise equivalent count rate (NECR) peak of 630 kcps is expected at 30 kBq cc −1 . Activity concentration and the sensitivity at the center amounts to 38 cps kBq −1 . The scatter fraction (SF) is estimated to 36.2 %. The values of SF and SR are comparable to those obtained for the state-of-the-art clinical PET scanners and the first total-body tomographs: uExplorer and PennPET. With respect to the standard PET systems with AFOV in the range from 16 to 26 cm, the TB-J-PET is characterized by an increase in NECR approximately by factor of 4 and by the increase of the whole-body sensitivity by factor of 12.6 to 38. The time-of-flight resolution for the TB-J-PET is expected to be at the level of CRT = 240 ps full width at half maximum. For the TB-J-PET with an AFOV of 140 cm, an image quality of the reconstructed images of a NEMA IEC phantom was presented with a contrast recovery coefficient and a background variability parameters. The increase of the whole-body sensitivity and NECR estimated for the TB-J-PET with respect to current commercial PET systems makes the TB-J-PET a promising cost-effective solution for the broad clinical applications of total-body PET scanners. TB-J-PET may constitute an economic alternative for the crystal TB-PET scanners, since plastic scintillators are much cheaper than BGO or LYSO crystals and axial arrangement of the strips significantly reduces the costs of readout electronics and SiPMs.

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Sensitivity of Discrete Symmetry Tests in the Positronium System with the J-PET Detector

Cited by 9 publications

References 51 publications

Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

Testing CPT symmetry in ortho-positronium decays with positronium annihilation tomography

Simulating NEMA characteristics of the modular total-body J-PET scanner—an economic total-body PET from plastic scintillators

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