Status of the X17 search in Montreal Azuelos, G.; Bryman, D.; Chen, W.C. ...
Journal of physics. Conference series,
12/2022, Letnik:
2391, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
At the Montreal Tandem accelerator, an experiment is being set up to measure internal pair creation from the decay of nuclear excited states using a multiwire proportional chamber and ...scintillator bars surrounding it from the Daphne experiment. The acceptance covers a solid angle of nearly 4π. Preamplifiers and the data acquisition hardware have been designed and tested. The
7
LiF target, mounted on an Al foil and water-cooled is in a thin carbon fiber section of the beamline. The experiment will focus at first on a measurement of the internal pair creation from the 18.15 MeV state of
8
Be with the aim of observing independently the X17 particle discovered by the ATOMKI experiment. Assuming the ATOMKI evaluation of the electron-pair production rate from X17, Geant4 simulation predicts observation of a clear signal after about 2 weeks of data taking with 2
μ
A proton beam. The IPC measurement could eventually be extended to the giant dipole resonance of
8
Be, as well as to other nuclei, in particular to
10
B.
In the present work of the PIENU experiment, heavy neutrinos were sought in pion decays π+→μ+ν at rest by examining the observed muon energy spectrum for extra peaks in addition to the expected peak ...for a light neutrino. No evidence for heavy neutrinos was observed. Upper limits were set on the neutrino mixing matrix |Uμi|2 in the neutrino mass region of 15.7–33.8 MeV/c2, improving on previous results by an order of magnitude.
The PIENU experiment aims to measure the branching ratio of the charged pion decay with precision of < 0.1 %. This measurement is much sensitive to search for massive neutrinos coupled to electrons ...in
π
+
→
e
+
ν
e
decay. The initial analysis was completed and the upper limit on the neutrino mixing parameter |
U
e
i
|
2
in the neutrino mass range of 0 to 55 MeV/
c
2
was improved by a factor of 1.5, and the sensitivity for the mass range of 68 to 129 MeV/
c
2
was improve by a factor of up to 4.
The imaging performance of a high-resolution preclinical micro-positron emission tomography (micro-PET) system employing liquid xenon (LXe) as the gamma-ray detection medium was simulated. The ...arrangement comprises a ring of detectors consisting of trapezoidal LXe time projection ionization chambers and two arrays of large area avalanche photodiodes for the measurement of ionization charge and scintillation light. A key feature of the LXePET system is the ability to identify individual photon interactions with high energy resolution and high spatial resolution in three dimensions and determine the correct interaction sequence using Compton reconstruction algorithms. The simulated LXePET imaging performance was evaluated by computing the noise equivalent count rate, the sensitivity and point spread function for a point source according to the NEMA-NU4 standard. The image quality was studied with a micro-Derenzo phantom. Results of these simulation studies included noise equivalent count rate peaking at 1326 kcps at 188 MBq (705 kcps at 184 MBq) for an energy window of 450-600 keV and a coincidence window of 1 ns for mouse (rat) phantoms. The absolute sensitivity at the center of the field of view was 12.6%. Radial, tangential and axial resolutions of (22)Na point sources reconstructed with a list-mode maximum likelihood expectation maximization algorithm were ≤0.8 mm (full-width at half-maximum) throughout the field of view. Hot-rod inserts of <0.8 mm diameter were resolvable in the transaxial image of a micro-Derenzo phantom. The simulations show that a LXe system would provide new capabilities for significantly enhancing PET images.
The pion branching ratio,
R
π
=
Γ
(
π
+
→
e
+
ν
e
+
π
+
→
e
+
ν
e
γ
)
Γ
(
π
+
→
μ
+
ν
μ
+
π
+
→
μ
+
ν
μ
γ
)
, provides a sensitive test of lepton universality and constraints on many new physics ...scenarios. The theoretical uncertainty on the Standard Model prediction of
R
π
is 0.02 %, a factor of twenty smaller than the experimental uncertainty. The analysis of a subset of data taken by the PIENU experiment will be presented. The result,
R
π
= (1.2344 ± 0.0023(
s
t
a
t
) ± 0.0019(
s
y
s
t
)) ⋅ 10
−4
1
, is consistent with the Standard Model prediction and represents a 0.1 % constraint on lepton non-universality.
Status of the PIENU experiment at TRIUMF Ito, S; Aguilar-Arevalo, A; Aoki, M ...
Journal of physics. Conference series,
07/2015, Letnik:
631, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The PIENU experiment at TRIUMF aims to measure the branching ratio of pion decays R = Γ(π+ → e+νe + π+ → e+ νeγ) Γ(π+→μ+νμ + π+ → μ+νμγ) with precision <0.1%, providing a stringent test of the ...Standard Model hypothesis of electron-muon universality and a search for new physics.
NA62 liquid krypton purity monitor Bremer, J.; Bryman, D.; Danielsson, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2023, Letnik:
1057
Journal Article
Recenzirano
Odprti dostop
A system for determining the purity of liquid krypton employed in the NA62 rare kaon decay experiment at CERN was developed based on the use of a time projection chamber. The attenuation of drifting ...ionization electrons from absorption of 511 keV gamma rays in liquid krypton was measured to estimate the purity. The setup was tested with krypton purified from commercial sources.
Purpose: A high‐resolution micro‐PET system based on liquid xenon (LXe) is under development. The system employs LXe time projection ionization detectors (TPC) and large‐area avalanche photodiodes ...(LAAPDs) light sensors. The energy and positions of interactions with the liquid xenon are measured by combining signals received from ionization charge in the TPC with scintillation light from the LAAPD arrays. The energy from scintillation light is used to select events in the 1st‐stage of a 2‐stage event selection. In this work we investigated methods of determining interaction locations from the LAAPD data by employing neural network (NN) computation algorithms. The position resolutions achievable by these methods under various degrees of reflectivity of the surfaces within the detector are presented. Methods: Simulations were performed using GEANT4 code. A simulated isotropic point source of 10220 optical photons (representing scintillation light from 511 keV gamma photons) was located at various points within the sector. The scintillation signal on the LAAPDs was calculated for all points within the sector on a 2×2×2 mm three dimensional grid for various levels of reflectivity. A random distribution of interactions within the sector was then evaluated with the NN algorithm. Results: The simulation studies indicate that under conditions of no optical reflectivity within the sector, interaction locations can be successfully reconstructed in 3 dimensions with approximately 8 mm FWHM 3‐D spatial resolution. When reflective surfaces are added to the inner walls of the sector, the position resolution is improved to 3.5 mm FWHM 3‐D spatial resolution, depending on the amounts and locations of the reflective surfaces. Conclusions: Scintillation position measurements of up to 3.5 mm FWHM 3‐D spatial resolution are achievable with various levels of surface reflectivity for the PET scanner employing LXeTPC detectors. Further analysis and techniques for improving signal to noise ratio in LAAPDs could improve the resolution.
PDF
