C. Wrede’s research while affiliated with Michigan State University and other places

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Publications (189)


Figure 1: Simplified decay sequence of 20 Mg showing relevant transitions. The 15 O(α, γ) 19 Ne reaction rate is primarily influenced by a resonance with a well-established center-of-mass energy of 506 keV, corresponding to the 4034 keV state in 19 Ne [3].
Figure 2: CAD drawing of the GADGET II detection system showing the direction a radioactive beam enters the TPC chamber. The GADGET II TPC is seen inside of the DEGAi germanium array [3].
Figure 3: Full GADGET II experimental setup used during FRIB experiment 21072 [3].
Figure 4: 2D MicroMegas pad plane images of 220 Rn alpha tracks (6.288 MeV) inside the GADGET II TPC [3].
Figure 5: a) 3D reconstruction of a real 6.288 MeV 220 Rn alpha track inside the GADGET II TPC. b) Closeup of the reconstruction with energy deposition showing a characteristic Bragg peak [3].

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Object Detection with Deep Learning for Rare Event Search in the GADGET II TPC
  • Preprint
  • File available

January 2025

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35 Reads

Tyler Wheeler

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S. Ravishankar

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C. Wrede

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[...]

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L. E. Weghorn

In the pursuit of identifying rare two-particle events within the GADGET II Time Projection Chamber (TPC), this paper presents a comprehensive approach for leveraging Convolutional Neural Networks (CNNs) and various data processing methods. To address the inherent complexities of 3D TPC track reconstructions, the data is expressed in 2D projections and 1D quantities. This approach capitalizes on the diverse data modalities of the TPC, allowing for the efficient representation of the distinct features of the 3D events, with no loss in topology uniqueness. Additionally, it leverages the computational efficiency of 2D CNNs and benefits from the extensive availability of pre-trained models. Given the scarcity of real training data for the rare events of interest, simulated events are used to train the models to detect real events. To account for potential distribution shifts when predominantly depending on simulations, significant perturbations are embedded within the simulations. This produces a broad parameter space that works to account for potential physics parameter and detector response variations and uncertainties. These parameter-varied simulations are used to train sensitive 2D CNN object detectors. When combined with 1D histogram peak detection algorithms, this multi-modal detection framework is highly adept at identifying rare, two-particle events in data taken during experiment 21072 at the Facility for Rare Isotope Beams (FRIB), demonstrating a 100% recall for events of interest. We present the methods and outcomes of our investigation and discuss the potential future applications of these techniques.

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Lifetimes and Branching Ratios Apparatus (LIBRA)

October 2024

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13 Reads

The Particle X-ray Coincidence Technique (PXCT) was originally developed to measure average lifetimes in the 1017101510^{-17}-10^{-15}~s range for proton-unbound states populated by electron capture (EC). We have designed and built the Lifetimes and Branching Ratios Apparatus (LIBRA) to be used in the stopped-beam area at the Facility for Rare Isotope Beams that extends PXCT to measure both lifetimes and decay branching ratios of resonances populated by EC/β+\beta^+ decay. The first application of LIBRA aims to obtain essential nuclear data from 60^{60}Ga EC/β+\beta^+ decay to constrain the thermonuclear rates of the 59^{59}Cu(p,γ)60(p,\gamma)^{60}Zn and 59^{59}Cu(p,α)56(p,\alpha)^{56}Ni reactions, and in turn, the strength of the NiCu nucleosynthesis cycle, which is predicted to significantly impact the modeling of Type I X-ray burst light curves and the composition of the burst ashes. Detailed theoretical calculations, Monte Carlo simulations, and performance tests with radioactive sources have been conducted to validate the feasibility of employing LIBRA for the 60^{60}Ga experiment. The method introduced with LIBRA has the potential to measure nearly all essential ingredients for thermonuclear reaction rate calculations in a single experiment, in the absence of direct measurements, which are often impractical for radioactive reactants.


Time projection chamber for GADGET II

September 2024

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29 Reads

Physical Review C

Background: The established Gaseous Detector with Germanium Tagging (GADGET) detection system is used to measure weak, low-energy β-delayed proton decays. It consists of the Gaseous Proton Detector equipped with a MICROMEGAS (MM) readout to detect protons and other charged particles calorimetrically, surrounded by the Segmented Germanium Array (SeGA) for high-resolution detection of prompt γ rays.


Figure 1. Fractional uncertainties to the V ud extraction from the most precise channels.
Figure 2. Projected sensitivities for heavy sterile neutrino searches in the eV -MeV mass range for current and planned experiments including the KATRIN/TRISTAN, Project-8, HUNTER, and the BeEST. Figure from Snowmass 2022 [87].
Nuclear β\beta decay as a probe for physics beyond the Standard Model

January 2023

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103 Reads

This white paper was submitted to the 2022 Fundamental Symmetries, Neutrons, and Neutrinos (FSNN) Town Hall Meeting in preparation for the next NSAC Long Range Plan. We advocate to support current and future theoretical and experimental searches for physics beyond the Standard Model using nuclear β\beta decay.


Horizons: nuclear astrophysics in the 2020s and beyond

November 2022

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915 Reads

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37 Citations

Nuclear astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities.


Horizons: Nuclear Astrophysics in the 2020s and Beyond

May 2022

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522 Reads

Nuclear Astrophysics is a field at the intersection of nuclear physics and astrophysics, which seeks to understand the nuclear engines of astronomical objects and the origin of the chemical elements. This white paper summarizes progress and status of the field, the new open questions that have emerged, and the tremendous scientific opportunities that have opened up with major advances in capabilities across an ever growing number of disciplines and subfields that need to be integrated. We take a holistic view of the field discussing the unique challenges and opportunities in nuclear astrophysics in regards to science, diversity, education, and the interdisciplinarity and breadth of the field. Clearly nuclear astrophysics is a dynamic field with a bright future that is entering a new era of discovery opportunities.


Constraining the P 30 ( p , γ ) S 31 Reaction Rate in ONe Novae via the Weak, Low-Energy, β -Delayed Proton Decay of Cl 31

May 2022

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44 Reads

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9 Citations

Physical Review Letters

The ^{30}P(p,γ)^{31}S reaction plays an important role in understanding the nucleosynthesis of A≥30 nuclides in oxygen-neon novae. The Gaseous Detector with Germanium Tagging was used to measure ^{31}Cl β-delayed proton decay through the key J^{π}=3/2^{+}, 260-keV resonance. The intensity I_{βp}^{260}=8.3_{-0.9}^{+1.2}×10^{-6} represents the weakest β-delayed, charged-particle emission ever measured below 400 keV, resulting in a proton branching ratio of Γ_{p}/Γ=2.5_{-0.3}^{+0.4}×10^{-4}. By combining this measurement with shell-model calculations for Γ_{γ} and past work on other resonances, the total ^{30}P(p,γ)^{31}S rate has been determined with reduced uncertainty. The new rate has been used in hydrodynamic simulations to model the composition of nova ejecta, leading to a concrete prediction of ^{30}Si:^{28}Si excesses in presolar nova grains and the calibration of nuclear thermometers.


FIG. 1. [Color online] 31 Cl β-delayed proton spectrum measured by only the central detector pad [black] and for eventlevel summing of the five inner detector pads [grey (pink online)] up to 1.5 MeV. The energy spectrum sums the ionization deposited in the P10 gas from both the decay protons and recoiling 30 P nuclei. β + particles are responsible for the large background at low energies and can also sum with ionization produced by proton tracks, leading to a detector response that is skewed to the right; this effect is larger in the combined-pad spectrum due to the effective increase in detection pad area.
FIG. 2. [Color online] (a) Contributions of individual resonances to the 30 P(p, γ) 31 S reaction rate and the total summed thermonuclear rate [solid black] plotted over peak nova temperatures. (b) The ratio between the experimental resonant reaction rate and the Hauser-Feshbach statistical rate [17]. The solid curve represents the recommended central rate, while the dashed curves indicate the upper and lower limits on the resonant rate calculation.
Constraining the 30^{30}P(p,γ)31p,\gamma)^{31}S reaction rate in ONe novae via the weak, low-energy, β\beta-delayed proton decay of 31^{31}Cl

April 2022

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62 Reads

The 30^{30}P(p,γ)31(p,\gamma)^{31}S reaction plays an important role in understanding nucleosynthesis of A30A\geq 30 nuclides in oxygen-neon novae. The Gaseous Detector with Germanium Tagging was used to measure 31^{31}Cl β\beta-delayed proton decay through the key Jπ=3/2+J^{\pi}=3/2^{+}, 260-keV resonance. The intensity Iβp260=8.30.9+1.2×106I^{260}_{\beta p} = 8.3^{+1.2}_{-0.9} \times 10^{-6} represents the weakest β\beta-delayed, charged-particle emission ever measured below 400 keV, resulting in a proton branching ratio of Γp/Γ=2.50.3+0.4×104\Gamma_p / \Gamma = 2.5^{+0.4}_{-0.3} \times 10^{-4}. By combining this measurement with shell-model calculations for Γγ\Gamma_{\gamma} and past work on other resonances, the total 30^{30}P(p,γ)31(p,\gamma)^{31}S rate has been determined with reduced uncertainty. The new rate has been used in hydrodynamic simulations to model the composition of nova ejecta, leading to a concrete prediction of 30^{30}Si/28^{28}Si excesses in presolar nova grains and the calibration of nuclear thermometers.


FIG. 1. Particle identification plot of the energy-loss (∆E) in the 87-µm Si detector versus the residual energy deposited in the 1-mm Si detector (E). Each locus of points represents a charged particle group or a coincidence summing of two groups.
First application of Markov Chain Monte Carlo-based Bayesian data analysis to the Doppler-Shift Attenuation Method

March 2022

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162 Reads

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2 Citations

Physics Letters B

Motivated primarily by the large uncertainties in the thermonuclear rate of the 30^{30}P(p,γ)31(p,\gamma)^{31}S reaction that limit our understanding of classical novae, we carried out lifetime measurements of 31^{31}S excited states using the Doppler Shift Lifetimes (DSL) facility at the TRIUMF Isotope Separator and Accelerator (ISAC-II) facility. The 31^{31}S excited states were populated by the 3^{3}He(32(^{32}S,α)31,\alpha)^{31}S reaction. The deexcitation γ\gamma rays were detected by a clover-type high-purity germanium detector in coincidence with the α\alpha particles detected by a silicon detector telescope. We have applied modern Markov chain Monte Carlo-based Bayesian methods to perform lineshape analyses of Doppler-Shift Attenuation Method γ\gamma-ray data for the first time. We have determined the lifetimes for the two lowest-lying 31^{31}S excited states. Upper limits on the previously unknown lifetimes of four higher-lying states have been obtained. The experimental results were compared to the shell-model calculations using five universal sd-shell Hamiltonians. The γ\gamma rays originating from the astrophysically important Jπ=3/2+J^\pi=3/2^+, 260-keV 30^{30}P(p,γ)31(p,\gamma)^{31}S resonance have also been observed, but the lifetime is expected to be better constrained with more statistics at the upgraded DSL2 facility.


Fig. 1. Left Panel: CAD drawing of the full GADGET II setup, including the beam-cross, SeGA array, and TPC. Middle Panel: Micromegas being installed on GADGET II TPC. Right Panel: Assembled AsAd box attached to the TPC.
Measuring the 15 O(α, γ) 19 Ne reaction in Type I X-ray bursts using the GADGET II TPC: Hardware

January 2022

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78 Reads

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2 Citations

The European Physical Journal Conferences

Sensitivity studies have shown that the ¹⁵ O(α, γ) ¹⁹ Ne reaction is the most important reaction rate uncertainty affecting the shape of light curves from Type I X-ray bursts. This reaction is dominated by the 4.03 MeV resonance in ¹⁹ Ne. Previous measurements by our group have shown that this state is populated in the decay sequence of ²⁰ Mg. A single ²⁰ Mg(βp α) ¹⁵ O event through the key ¹⁵ O(α, γ) ¹⁹ Ne resonance yields a characteristic signature: the emission of a proton and alpha particle. To achieve the granularity necessary for the identification of this signature, we have upgraded the Proton Detector of the Gaseous Detector with Germanium Tagging (GADGET) into a time projection chamber to form the GADGET II detection system. GADGET II has been fully constructed, and is entering the testing phase.


Citations (56)


... Exotic nuclei, which must be produced in radioactive ion beam facilities and studied before they decay, are often investigated through reaction processes [1,2]. Reactions are not only crucial for understanding nuclei but also play a significant role in various astrophysical phenomena, such as stellar burning and nucleosynthesis [3,4]. ...

Reference:

Nuclear cross sections from low-energy interactions
Horizons: nuclear astrophysics in the 2020s and beyond

... In these cases, indirect experimental approaches can already dramatically reduce reaction rate uncertainties. These include beta-delayed particle emission, for example with the GADGET active target system [822], and (d,n) transfer reactions using the GRETINA gamma detection array with the LENDA neutron-detection array [823]. ...

Constraining the P 30 ( p , γ ) S 31 Reaction Rate in ONe Novae via the Weak, Low-Energy, β -Delayed Proton Decay of Cl 31
  • Citing Article
  • May 2022

Physical Review Letters

... Later, further lifetime investigations in 106 Ag were performed by three research groups. Ref. [57] reported that the deduced and rates in the two bands are similar, while Ref. [58] suggested these two lowest-lying bands have different configurations. Zheng et al. [26] also performed the lifetime measurements to determine whether or not the candidate chiral doublet bands of 106 Ag are in agreement with the chiral fingerprints. ...

First application of Markov Chain Monte Carlo-based Bayesian data analysis to the Doppler-Shift Attenuation Method

Physics Letters B

... The highgranularity readout plane consists of 1024 square pads, 1016 of which are used for tracking reconstruction, while 8 are used as vetos. A high-density Generic Electronics for TPCs (GET) data acquisition system [22] has been installed to cover an electronic channel per pad [23,24]. This increases the number of measurement pads by over a factor of 200 as compared to the Proton Detector which had only 5 measurement pads. ...

Measuring the 15 O(α, γ) 19 Ne reaction in Type I X-ray bursts using the GADGET II TPC: Hardware

The European Physical Journal Conferences

... The device is currently under construction and is expected to begin measurements in 2024. Other studies of the αbranching ratio are also being pursued by the GADGET group [31,32] and using the SABRE detector [33]. While indirect techniques are important, many reactions in the αp process can be measured directly at existing or future exotic beam facilities. ...

Measuring the 15 O( α , γ ) 19 Ne Reaction in Type I X-ray Bursts using the GADGET II TPC: Software

The European Physical Journal Conferences

... The spectrum features a prominent peak at 3046(3) keV, corresponding to the transition of the 2 + 1 state to the ground state. Testament to the proximity of the proton dripline, the low proton-decay threshold of 36 Ca of S p = 2600(6) keV [26,27] leaves the 2 + 1 state with a small proton decay branch in addition to the γ emission. In agreement with previous γ -ray spectroscopy [12,28,29], no transitions from the other excited states reported in Ref. [10] are observed. ...

First Penning trap mass measurement of Ca 36
  • Citing Article
  • January 2021

Physical Review C

... GADGET is an operational detection system at the National Superconducting Cyclotron Laboratory (NSCL)/FRIB consisting of the gaseous Proton Detector surrounded by the Segmented Germanium Array (SeGA) of High Purity Germanium (HPGe) γ-ray detectors. It has been used at the NSCL for calorimetric measurements of low-energy β-delayed protons in cases where particle identification is not needed [9][10][11][12]. For example, this system has been used by Budner et al. [9] to study the β-decay of 31 Cl to probe the 30 P (p, γ) 31 S reaction leading to the measurement of a 260-keV resonance which represents the weakest β-delayed, charged-particle intensity ever measured below 400 keV. ...

Si 25 β + -decay spectroscopy
  • Citing Article
  • January 2021

Physical Review C

... The cross-shell p-sd-p f model space is necessary for the description of negative parity resonances in sd-shell nuclei (see, e.g., Refs. [159,160]). ...

Shell-model studies of the astrophysical rp-process reactions 34 S(p,γ) 35 Cl and 34 g,m Cl(p,γ) 35 Ar

Journal of Physics Conference Series

... SeGA, GRETINA (and GRETA in the future), and Gammasphere] [374,375,[412][413][414][415], γ-particle coincidence techniques (e.g. GODDESS) [416,417], the Trojan Horse reaction Method [114], the asymptotic normalization coefficient method [418], elastic scattering [419,420], Coulomb breakup [255,421], constraints on statistical nuclear properties (e.g. with ( 3 He, n) neutron time-offlight measurements at Ohio University and the University of Notre Dame) [422,423], as well as charged-particle spectroscopy with high-resolution charged particle detector arrays [424,425] and the recently refurbished split-pole spectrographs at TUNL [426,427], Florida State University [428], and University of Notre Dame [429]. ...

Level structure of S 31 via S 32 ( p , d ) S 31
  • Citing Article
  • October 2020

Physical Review C

... where we note that the neutron lifetime anomaly is roughly a 1% effect [10]. 2 Direct experimental limits on n → χγ [55] and n → χe þ e − [56] decays also exist, removing ranges of parameter space as an explanation of the anomaly. We will be able to set much more severe limits through our studies, where we note the limit on Λ → χγ from SN1987 for Ref. [16]. ...

Search for neutron dark decay: n → χ + e + e

The European Physical Journal Conferences