In a 2016 paper, an anomaly in the internal pair creation on the
M1
transition depopulating the 18.15 MeV isoscalar 1+ state on 8Be was observed. This could be explained by the creation and ...subsequent decay of a new boson, with mass
m
X
c
2
= 16.70 MeV. Further experiments of the same transition with an improved and independent setup were performed, which constrained the mass of the X17 boson (
m
X
c2) and its branching ratio relative to the γ-decay of the 8Be excited state (
B
X
), to
m
X
c
2
= 17.01(16) MeV and
B
X
= 6(1) 10−6, respectively. Using the latter setup, the
e
+
e
− pairs depopulating the 21 MeV
J
π = 0
−
0
+
transition in 4He were investigated and a resonance in the angular correlation of the pairs was observed, which could be explained by the same X17 particle, with mass
m
X
c
2
= 16.98 ± 0.16(stat) ± 0.20(syst) MeV.
An electron–positron pair spectrometer has been designed and constructed for the simultaneous measurement of energy- and angular correlations of e+e- pairs. Experimental results are obtained over a ...wide angular range for high-energy transitions in 16O, 12C and 8Be. The results showed that the angular correlations between 50 and 180°of the e+e- pairs in the energy range between 6 and 18MeV can be determined with sufficient resolution and efficiency in good agreement with the GEANT simulations.
Recently, we observed an anomalous peak-like excess of internal e+e− pairs at around 140° for the M1 transition depopulating the 18.15 MeV isoscalar 1+ state in 8Be. The deviation from the ...theoretical prediction can be described by GEANT simulations assuming the creation and subsequent decay of a new, light boson with a mass of 16.7 MeV/c2. In order to reduce the possible systematic errors from the experimenntal data, we re-investigated the 8Be anomaly with an improved setup and confirmed the anomaly within the statistical uncertainties. We also studied the angular correlation of the electron-positron pairs created in the M0 transition depopulating the 21.01 MeV 0− state in 4He, and observed an anomalous excess of e+e− pairs at a significantly smaller angle of 115°. Since the transition energy was higher in this case, the observed anomaly could be described by assuming the creation and subsequent decay of the same light particle in the simulations.
A new light particle is being born Krasznahorkay, A.J.; Begala, M.; Csatlós, M. ...
Journal of physics. Conference series,
12/2022, Letnik:
2391, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
A few years ago we observed anomalous electron-positron angular correlations for the 18.15 MeV M1 transition of
8
Be. This was interpreted as the creation and decay of an intermediate ...bosonic particle with a mass of
m
0
c
2
=16.70±0.35(stat )±0.5(sys) MeV, which is now called X17. The possible relation of the X17 boson to the dark matter problem triggered an enormous interest in the wider physics community. We also observed a similar anomaly in
4
He, which could be described also by the creation and subsequent decay of the same X17 particle. Very recently, the
11
B proton capture reaction was used for exciting the 17.2 MeV broad (Γ=1.15 MeV) resonance in
12
C and studying their internal pair creation decay. Anomalies were observed in the angular correlation of the electron-positron pairs, which together with the
8
Be and
4
He data provides kinematic evidence for the X17 particle and supports their vector boson and fifth force explanation.
Abstract
A detailed geometry description is essential to any high quality track reconstruction application. In current C++ based track reconstruction software libraries this is often achieved by an ...object oriented, polymorphic geometry description that implements different shapes and objects by extending a common base class. Such a design, however, has been shown to be problematic when attempting to adapt these applications to run on heterogeneous computing hardware, particularly on hardware accelerators. We present detray, a compile time polymorphic and yet accurate track reconstruction geometry description which is part of the ACTS parallelization R&D effort. detray is built as an index based geometry description with a shallow memory layout, that uses variadic template programming to allow custom shapes and intersection algorithms rather than inheritance from abstract base classes. It is designed to serve as a potential geometry and navigation backend for ACTS and as such implements the ACTS navigation model of boundary portals and purely surface based geometric entities. detray is designed to work with a dedicated memory management library and thus can be instantiated as a geometry model in host and device code.
Abstract
Programmers using the C++ programming language are increasingly taught to manage memory implicitly through containers provided by the C++ standard library. However, heterogeneous programming ...platforms often require explicit allocation and deallocation of memory. This discrepancy in memory management strategies can be daunting and problematic for C++ developers who are not already familiar with heterogeneous programming. The C++17 standard introduces the concept of
memory resources
, which allow the user to control how standard library containers allocate memory; we believe that this addition to the C++17 standard is a powerful tool towards the unification of memory management for heterogeneous systems with best-practice C++ development. In this paper, we present
vecmem
, a library of memory resources which allows efficient and user-friendly allocation of memory on CUDA, HIP, and SYCL devices through standard C++ containers. We investigate the design and use cases of such a library, the potential performance gains over naive memory allocation, and the limitations of this memory allocation model.
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