Beta Spectrum Research Articles

Experimental and theoretical study of 90Sr/90Y-n-Si/ZnO betavoltaic battery and theoretical prediction of homojunction betavoltaic cells performance

Today, betavoltaic batteries has been considered due to their high energy density and long life for operating electrical systems in inaccessible and hostile environments. Conventional electrochemical batteries, despite their widespread use in electronic devices, have a limited lifetime and tend to degrade in extreme environmental conditions. The current paper pursues three goals. The first goal is to the experimental and theoretical investigation of a n-Si/ZnO heterojunction betavoltaic battery based on 90Sr/90Y source. The second goal is to optimize ZnO, SnO2, BN, and diamond homojunction betavoltaic cells in two planar and cubical models by Monte Carlo simulation (MCNP code). The third goal is to present a new approach for estimating the standard error in calculating the parameters of betavoltaic batteries. In order to fabrication of a n-Si/ZnO heterojunction, the ZnO nanospheres were placed on the n-Si (100) substrate using chemical bath deposition (CBD) technology. The Al and Au electrodes were deposited on the formed sample. Then this sample was exposed to the radiation of an external 90Sr/90Y source with an activity of 12.8 mCi. The experimental values obtained for the short circuit current (Isc), open circuit voltage (Voc), efficiency (η), and maximum output power (Pmax) were 0.047 μA, 0.015 V, 3.4 × 10−4 percent, and 0.141 nW, respectively. To compare with the experiment, we investigated the n-Si/ZnO betavoltaic cell by MCNP code. In the simulation, the beta spectrum of the 90Sr/90Y source was considered. The calculated theoretical values for Isc, Voc, η, and Pmax were 0.063 μA, 0.020 V, 6.4 × 10−4 percent, and 0.265 nW, respectively. The experimental results show that the simulation results can be valid. In the optimization of ZnO, SnO2, BN, and diamond homojunction betavoltaic cells in two planar and cubical models by MCNP code, it was found that the Isc, Voc, η, and Pmax of the cubical model are better compared to the planar model. In the cubical model, Pmax of ZnO, SnO2, BN, and diamond betavoltaic batteries is 2633.34 nW ± 0.16 %, 1670.49 nW ± 0.15 %, 198.20 nW ± 0.17 %, and 1315.24 nW ± 0.15 %, respectively. In other words, Pmax of the ZnO betavoltaic battery is about 58 %, 1229 %, and 100 % more than Pmax of SnO2, BN, and diamond betavoltaic batteries, respectively. Pmax of the SnO2 betavoltaic battery is about 743 % and 27 % more than Pmax of BN and diamond betavoltaic batteries, respectively. The results show that ZnO and SnO2 betavoltaic batteries can perform better compared to BN and diamond betavoltaic batteries. Also, their growth process is less expensive compared to BN and diamond.

Optimization of the Electron Spectrometer Telescope geometry for the PRESET satellite through Monte Carlo simulation

The Electron Spectrometer Telescope (EST) aboard the PRESET satellite mission aims to measure the pitch angle distribution of 0.3–4 MeV electrons in the outer Van Allen belts. The PRESET satellite is planned to launch into a sun-synchronous low Earth orbit in Q2, 2026. We present comprehensive Monte Carlo simulations to optimize the design and response of the EST instrument. The EST consists of a stack of silicon strip detectors and a collimator to take pitch-angle dependent electron spectral measurements with a target angular resolution of 6° while rejecting the proton, heavy ion and gamma detection events. Various collimator designs and detector stacking configurations are investigated using the Geant4 code to deduce an optimal design and configuration. For validation of the Geant4 simulations, a benchmark test spectrometer was set up using a stack of four silicon detectors and a good agreement between the measured and simulated responses was found for a beta spectrum from a 90Sr/90Y source. The collimator design was optimized by adjusting total length, aperture size, number of view-ports and collimator materials. The optimum aperture size and the number of view-ports were determined by varying them and selecting the best cases that meet the angular resolution and the geometric factor requirements. Moreover, to address the under-utilization of the front position-sensitive detector encountered in a typical pin-hole collimator, two offset collimators with tilted axes were employed. Extensive simulations were carried out by varying the number of silicon detectors and the thickness of each detector to optimize the configuration of the silicon detector stack. An optimum thickness of the front detector was found to be 140 µm, which can minimize the perturbation counts caused by the proton detection events. For the other detectors, a stack of four 1.5 mm thick detectors was chosen to achieve a good sensitivity to low energy electrons at a tolerable complexity of the system. The angular response simulated for the optimum design of the EST showed a resolution of 5.5°, which is slightly better than the target resolution of 6°. The response matrices of the final design simulated for isotropic electron and proton fields showed a high geometric factor, which is expected to produce an average electron counting rate of 230 cps within the trapped region with a negligible contamination of the electron spectrum by protons except for a mild contamination by the 1.0–1.1 MeV protons.

Enhancement of beta spectrometry using double scintillators and ML-based unfolding

We present a novel beta spectrometer that consists of two identical plastic scintillators with one scintillator screened by a thin copper plate as a beta shield. The screened scintillator responds only to gamma photons while the other scintillator responds to both beta particles and gamma photons. The spectrometer’s response to beta and gamma radiations was characterized by experiments and Monte Carlo simulations. The gamma responses of the scintillators were in good agreement in most energy region while the screened scintillator showed a notable gamma attenuation in the low energy region below 150 keV. Comparison of the simulated and measured pulse height spectra showed good agreements for both beta and gamma radiations. For beta spectrum analysis, a simple gamma subtraction method and a convolutional neural network (CNN)-based method were investigated for various mixed beta–gamma fields. The subtraction method showed good accuracy in most energy regions while a notable overestimation of beta fluence was observed in the low energy region, which was caused by the gamma attenuation effect of the screened scintillator. The outcomes of the CNN method showed good agreements with the true beta fluence spectra for the validation dataset, however, the CNN model led to a significant overestimation for a dataset produced using the radionuclides that have not been used in the training datasets. To take the advantages of the outperforming features of both unfolding methods, a hybrid algorithm was deduced by applying a tolerance range to the subtraction result.

Unfolding experimental distortions in beta spectrometry

The distortions of measured beta spectra are addressed by means of unfolding algorithms. Two different approaches, the Maximum-Likelihood Expectation-Maximization and the Tikhonov regularization, are tested on various simulated spectra, for which the initial spectrum to retrieve is known, and on a 99Tc spectrum measured with our dedicated setup. Statistical uncertainties of distorted measured spectra are propagated by determining the covariance matrices. Both algorithms provide satisfactory results but Tikhonov performs overall better for most of the studied radionuclides. Highlight is made on the necessity to employ at least two independent methods to ensure the accuracy of the unfolded spectra and to estimate the internal bias of each algorithm.

Performance of gas electron tracking detectors for beta decay studies

At the low-energy frontier, among the experiments testing the Standard Model and searching for new physics, are precision spectrum shape and correlation coefficient measurements in nuclear and neutron beta decay. For identification and 3D-tracking of low-energy electrons, a special type of gas-based detector was designed that minimizes scattering and energy loss. First, the newly developed gas tracker was successfully used to study tiny effects in the beta spectrum shape for allowed Gamow-Teller transitions. The miniBETA spectrometer consists of a hexagonally structured multi-wire drift chamber (MWDC) filled with a mixture of helium and isobutane gas and a plastic scintillator serving as a trigger source and energy detector. The drift time information is used to establish the electron tracks in the plane perpendicular to the wires, while the charge division technique provides spatial information along the wires. Second, inspired by the performance of this spectrometer we are building a Mott polarimeter to be used in the BRAND experiment to study the neutron decay correlation coefficients.

Improving instrumental neutron activation analysis detection limit using Monte Carlo simulation for lanthanides determination in Algerian phosphate

ABSTRACT Instrumental Neutron Activation Analysis (INAA) is one of the best methods to analyse Rare Earth Elements (REE) with a low detection limit in phosphate samples. Since most lanthanides emit gamma rays at the energy below 1000 keV, this energy range is affected by the Bremsstrahlung noise of beta emission produced by the 31P(n,γ)32P reaction, when the irradiation of the P2O5 composing the phosphate matrix (approximately 30%). This beta (β−) spectrum with a maximum energy of 1.71 MeV (average energy of 695 keV) affects the gamma spectrum and will reduce the detection limit significantly, other factors decrease the detection limit of lanthanides like neutron self-shielding and interference. In the present work, an analysis methodology based on optimising the measurement parameters of the INAA technique was implemented to improve the detection limits for the precise evaluation of lanthanide concentrations in Algerian phosphate deposits. The complete procedure was developed using a combination of a Monte Carlo simulation approach and experimental measurements. Two models were developed based on Monte Carlo simulation for the calibration of HPGe detector efficiency and the optimisation of type and filter thickness to reduce the beta spectrum (Bremsstrahlung) emitted by the 32P produced by neutron capture reaction 31P(n, γ) 32P. The developed model allowed a considerable improvement in the detection limit of the INAA technique and reduced the uncertainty in the lanthanide concentration. Finally, the methodology was applied to determine lanthanide elements in phosphate samples with good precision.

Optimization and characterization of a coincidence beta-ray spectrometer

Aimed at beta spectrometry and dosimetry for mixed beta-gamma fields, a Si-plastic scintillator coincidence beta-ray spectrometer has been developed. The spectrometer collects pure beta-ray spectra by rejecting the gamma-ray detection events through coincidence. Both pulse height and arrival time of each detection event were recorded in list mode by a compact digital processing system. Spectral measurements were carried out using mixed beta-gamma fields from 90Sr/90Y and 137Cs sources for various beta and gamma count rates to evaluate the system performance. Coincidence beta spectra were collected for four fixed beta count rates (7.3–241 cps) from 90Sr/90Y while the gamma count rate from 137Cs was varied from 500 to 8000 cps. The coincidence beta spectrum was stable and unperturbed by the gamma detection events for most measurements while notable perturbation was observed in the low energy region when the beta to gamma count ratio is very low.

Primary standardization and Monte Carlo modeling of (243Am + 239Np) by means of a 4π(PC)-γ coincidence counting system

The procedure followed by the Nuclear Metrology Laboratory (LMN) at the IPEN for the primary standardization of a (243Am + 239Np) solution, in secular equilibrium, is described. The measurement was carried out in a 4π(PC) (α,β)−γ coincidence system. The total activity per unit mass of the solution was determined by the extrapolation technique, using a software coincidence counting systsem. The extrapolation curves were compared with Monte Carlo calculations by means of Code ESQUEMA, used in previous works, which, was improved and applied in order to calculate the alpha, beta, gamma, X-rays and coincidence spectra.

Measurement of the 171Tm beta spectrum

The beta spectrum of the main transition of the β- decay of 171Tm was measured using a double focalizing spectrometer. The instrument was lately improved in order to reduce its low energy threshold to 34 keV. We used the spectrometer to measure the beta spectrum end-point energy of the main transition of 171Tm decay using the Kurie plot formalism. We report a new value of 97.60(38) keV, which is in agreement with previous measurements. In addition, the spectrum shape was compared with the ξ-approximation calculation where the shape factor is equal to 1 and good agreement was found between the theory and the measurement at the 1% level.

Monte Carlo dosimetry of a novel Yttrium-90 disc source for episcleral brachytherapy.

To calculate the dose distribution using Monte Carlo simulations for a novel high-dose-rate Yttrium-90 (Y-90) disc source recently developed for episcleral brachytherapy and provide a lookup table for treatment planning. Monte Carlo simulations were performed to calculate the in-water dose distribution of the Y-90 disc source using the "GATE", a software based on the "Geant4" Monte Carlo simulation toolkit developed by the international OpenGATE collaboration. The geometry of this novel beta source, its capsule, and the surrounding water medium were accurately modeled in the simulation input files. The standard Y-90 element beta spectrum from ICRU 72 was used, and the physics processes for beta and photon interactions with matters were all included. The dose distribution of this Y-90 disc source was measured in a separate study using Gafchromic EBT-3 films and the results were reported elsewhere. To match the setup of the experiment, a Gafchromic EBT-3 film was also included in the simulation geometry. The simulated dose profiles were exported from the 3D dose distribution results and compared with the measured dose profiles. Transverse dose profiles at different distances from the seed surface were also obtained to study the lateral coverage of the source. The measured percent depth dose (PDD) curves along the central axis perpendicular to the surface of the Y-90 disc were constructed from the experimental and simulated data, and normalized to the reference point at 1mm from the source capsule. Both PDD curves agreed well up to 4mm from the source surface (maximum difference±10%) but deviated from each other beyond 4mm. The deviation might be caused by the increased measurement uncertainty in the low-dose region. The dose rate at the reference point calculated from the Monte Carlo simulation was 1.09cGy/mCi-s and agreed very well with the measured dose rate of 1.05cGy/mCi-s. If the 80% isodose line is selected as the lateral coverage, the lateral dose coverage is maximal (∼4.5mm) at the plane next to the source surface, and gradually decreases with the increasing distance, approaching 3.5mm when the plane is 5mm from the 6-mm diameter source surface. Monte Carlo simulations were successfully performed to confirm the measured PDD curve of the novel Y-90 disc source. This simulation work laid a solid foundation for characterizing the full dosimetry parameters of this source for episcleral brachytherapy applications.

Tritium Beta Spectrum Measurement and Neutrino Mass Limit from Cyclotron Radiation Emission Spectroscopy.

The absolute scale of the neutrino mass plays a critical role in physics at every scale, from the subatomic to the cosmological. Measurements of the tritium end-point spectrum have provided the most precise direct limit on the neutrino mass scale. In this Letter, we present advances by Project 8 to the cyclotron radiation emission spectroscopy (CRES) technique culminating in the first frequency-based neutrino mass limit. With only a cm^{3}-scale physical detection volume, a limit of m_{β}<155 eV/c^{2} (152 eV/c^{2}) is extracted from the background-free measurement of the continuous tritium beta spectrum in a Bayesian (frequentist) analysis. Using ^{83m}Kr calibration data, a resolution of 1.66±0.19 eV (FWHM) is measured, the detector response model is validated, and the efficiency is characterized overthe multi-keV tritium analysis window. These measurements establish the potential of CRES for a high-sensitivity next-generation direct neutrino mass experiment featuring low background and high resolution.

Study of weak magnetism by precision spectrum shape measurements in nuclear beta decay

Nuclear beta decays play an important role in uncovering the nature of the weak interaction. The weak magnetism (WM) form factor, b WM, is generally a small correction to the beta decay rate that arises at first order as an interference term between the dominant Gamow-Teller and the magnetic dipole contributions to the weak current. This form factor is still poorly known for nuclei with higher atomic number. We performed a careful analysis of the measured beta spectrum shape for Gamow-Teller transitions in 114In and 32P nuclei. The precision spectrum shape measurements were carried out using the miniBETA spectrometer consisting of a low-mass, low-Z multi-wire gas tracker and a plastic scintillator energy detector. The preliminary results for the weak magnetism extraction for 114In and 32P nuclei are presented.

Activity standardization of 60Co and 106Ru/106Rh by means of the TDCR method and the importance of the beta spectrum

Atomic and nuclear data represent an important input for the accuracy of primary activity measurements based on liquid scintillation. In particular, the reliability of β-spectrum computation has been investigated for several years through experimental and theoretical studies providing solid evidence for the need to consider the atomic effects. In the present study, the activity standardization of two β-emitting radionuclides (60Co, 106Ru/106Rh) was carried out by means of the 4πβ−γ coincidence and Triple-to-Double Coincidence Ratio (TDCR) methods. The comparison between the activity concentrations given by both primary techniques presents new evidence that a better agreement is obtained when the exchange and screening effects are included in the β-spectra implemented in the model of light emission for TDCR measurements. A new development of a stochastic model based on Geant4 simulations for TDCR calculations is also presented.

Investigation of a Beta Spectrum through Virtual MCA Supported By Virtual Oscilloscope

In this study, the performance of a developed virtual MCA (Multichannel Analyzer) was tested in a beta spectrometer. A real MCA was also used in the spectrometer to compare the results from the virtual one. The beta energy spectrum of a 204Tl radioactive source was displayed in the real and virtual MCAs. Total counts in the spectra from both MCAs were determined for different data acquisition times. In addition to the total counts, spectrum shapes, starting and ending channel numbers of the beta spectrum from the virtual MCA were also compared with those of the real one. Besides, an oscilloscope feature was brought in to the virtual MCA different from the conventional ones. The output signal shapes of a main amplifier through the detector were displayed in a real oscilloscope and the developed virtual oscilloscope to test this feature. It was noticed that results from both MCAs and oscilloscopes were highly compatible with each other. It is concluded that the developed virtual MCA supported by the virtual oscilloscope could be used like a real one.

From MEG to clinical EEG: evaluating a promising non-invasive estimator of defense-related muscle sympathetic nerve inhibition

Sudden, unexpected stimuli can induce a transient inhibition of sympathetic vasoconstriction to skeletal muscle, indicating a link to defense reactions. This phenomenon is relatively stable within, but differs between, individuals. It correlates with blood pressure reactivity which is associated with cardiovascular risk. Inhibition of muscle sympathetic nerve activity (MSNA) is currently characterized through invasive microneurography in peripheral nerves. We recently reported that brain neural oscillatory power in the beta spectrum (beta rebound) recorded with magnetoencephalography (MEG) correlated closely with stimulus-induced MSNA inhibition. Aiming for a clinically more available surrogate variable reflecting MSNA inhibition, we investigated whether a similar approach with electroencephalography (EEG) can accurately gauge stimulus-induced beta rebound. We found that beta rebound shows similar tendencies to correlate with MSNA inhibition, but these EEG data lack the robustness of previous MEG results, although a correlation in the low beta band (13–20 Hz) to MSNA inhibition was found (p = 0.021). The predictive power is summarized in a receiver-operating-characteristics curve. The optimum threshold yielded sensitivity and false-positive rate of 0.74 and 0.33 respectively. A plausible confounder is myogenic noise. A more complicated experimental and/or analysis approach is required for differentiating MSNA-inhibitors from non-inhibitors based on EEG, as compared to MEG.

Calculation the difference created in Monte Carlo simulation results due to the use of the average energy of a beta source instead of its continuous beta spectrum

Calculation the difference created in Monte Carlo simulation results due to the use of the average energy of a beta source instead of its continuous beta spectrum

Hyperarousal-state of Insomnia Disorder in Wake-resting State Quantitative Electroencephalography.

: Insomnia is associated with elevated high-frequency electroencephalogram power in the waking state. Although affective symptoms (e.g., depression and anxiety) are commonly comorbid with insomnia, few reports distinguished objective sleep disturbance from affective symptoms. In this study, we investigated whether daytime electroencephalographic activity explains insomnia, even after controlling for the effects of affective symptoms. : A total of 107 participants were divided into the insomnia disorder (n = 58) and healthy control (n = 49) groups using the Mini-International Neuropsychiatric Interview and diagnostic criteria for insomnia disorder. The participants underwent daytime resting-state electroencephalography sessions (64 channels, eye-closed). : The insomnia group showed higher levels of anxiety, depression, and insomnia than the healthy group, as well as increased beta [t(105) = -2.56, p = 0.012] and gamma [t(105) = -2.44, p = 0.016] spectra. Among all participants, insomnia symptoms positively correlated with the intensity of beta (r = 0.28, p ＜ 0.01) and gamma (r = 0.25, p ＜ 0.05) spectra. Through hierarchical multiple regression, the beta power showed the additional ability to predict insomnia symptoms beyond the effect of anxiety (ΔR2 = 0.041, p = 0.018). : Our results showed a significant relationship between beta electroencephalographic activity and insomnia symptoms, after adjusting for other clinical correlates, and serve as further evidence for the hyperarousal theory of insomnia. Moreover, resting-state quantitative electroencephalography may be a supplementary tool to assess insomnia.

A universal energy response model for determining the energy nonlinearity and resolution of e^pm and gamma in liquid scintillator detectors

Energy nonlinearity and resolution in liquid scintillator (LS) detectors are correlated and particle-dependent. A unified energy response model for liquid scintillator detectors has been presented in details. This model has advanced a data-driven approach to calibrate the particle-dependent energy response, using both the monoenergetic gamma -ray sources and the continuous beta spectra of ^textrm{12}textrm{B} and Michel e^- induced by cosmic muons. Monte Carlo studies have demonstrated the effectiveness and robustness of the proposed model, in particular, the positron energy resolution can be extracted in the absence of positron sources. This work will provide a feasible approach of simultaneous calibration of energy nonlinearity and resolution for the running and future LS detectors.

Development of a 4[formula omitted] detection system for the measurement of the shape of [formula omitted] spectra

The need of precise measurements of the energy distribution of emitted β particles has been addressed developing a specific detection system. An ultra-thin radioactive source, prepared on purpose, is enclosed between two silicon detectors in a compact geometry with a quasi-4π sr solid angle. The remaining distortions have been corrected with a dedicated deconvolution process based on mono-energetic Monte Carlo simulations that are used to build the response matrix. The β spectra from 14C and 204Tl decays have been measured and analyzed. Extracted maximum energies are fully consistent with the AME2020 recommended Q-values. A linear slope of a = −0.430 (37) MeV−1 that comes from the weak magnetism term in the 14C beta spectrum has been determined, in excellent agreement with the theoretical predictions. The measured range of the 204Tl beta spectrum has been extended down to 60 keV and a shape factor (dq2+λ2p2) has been extracted with d=1.075 (13).

Beta spectrum shape studies for the predictions of the antineutrino spectrum from reactors

Nuclear reactors antineutrino measurements at short baselines do not fully agree with model predictions calculated with the Conversion Method. An alternative method to calculate the antineutrino spectra is theSummation Method. Both methods require the shapes of beta spectra as inputs. For that reason a new setup to measure the shape of the beta spectrum of relevant fission products for the calculation of the antineutrino spectra of reactors has been developed. Some preliminary measurements performed at IGISOL with isotopically clean beams are presented in this contribution.