Alex Crowell

Journal Article Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics · December 10, 2022 We report the most precise determination of the S01 neutron-neutron effective range parameter (rnn) from neutron-neutron quasifree scattering in neutron-deuteron breakup. The experiment setup utilized a collimated beam of 15.5 MeV neutrons and an array of ... Full text Cite

Neutron-neutron quasifree scattering in neutron-deuteron breakup at 10 MeV

Journal Article Physical Review C · March 1, 2020 New measurements of the neutron-neutron quasifree scattering cross section in neutron-deuteron breakup at an incident neutron energy of 10.0 MeV are reported. The experiment setup was optimized to evaluate the technique for determining the integrated beam- ... Full text Cite

Design of an Experiment to Measure ann Using ³ H (γ, pn) n at HIγS

Conference EPJ Web of Conferences · March 25, 2016 We provide an update on the development of an experiment at TUNL for determining the 1S0 neutron-neutron (nn) scattering length (ann) from differential cross-section measurements of three-body photodisintegration of the triton. The experiment will be condu ... Full text Cite

Monte-Carlo Simulation of ³H(γ, pn) n and ³He(γ, pp) n Experiments at HI γs

Conference EPJ Web of Conferences · March 25, 2016 We are developing an experiment to measure the two and three-body (γ, p) differential cross sections (DCS) for 3H and 3He. These data will be used to determine the 1S0 nn scattering length (ann) and np scattering length (anp) respectively. This paper descr ... Full text Cite

Neutron-neutron quasifree scattering in nd breakup at 10 MeV

Conference EPJ Web of Conferences · March 25, 2016 The neutron-deuteron (nd) breakup reaction provides a rich environment for testing theoretical models of the neutron-neutron (nn) interaction. Current theoretical predictions based on rigorous ab-initio calculations agree well with most experimental data f ... Full text Cite

Measurement of the half-life of the T= 12 mirror decay of Ne 19 and its implication on physics beyond the standard model

Journal Article Physical Review Letters · May 27, 2014 The 12+→12+ superallowed mixed mirror decay of Ne19 to F19 is excellently suited for high precision studies of the weak interaction. However, there is some disagreement on the value of the half-life. In a new measurement we have determined this quantity to ... Full text Cite

Neutron-deuteron analyzing power data at En=22.5 MeV

Conference Physical Review C - Nuclear Physics · May 12, 2014 We present measurements of n-d analyzing power, Ay(θ), at En=22.5 MeV. The experiment uses a shielded neutron source which produced polarized neutrons via the 2H(d - ,n - )3He reaction. It also uses a deuterated liquid-scintillator center detector and six ... Full text Cite

Nuclear physics detector technology applied to plant biology research

Journal Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment · January 1, 2013 The ability to detect the emissions of radioactive isotopes through radioactive decay (e.g. beta particles, x-rays and gamma-rays) has been used for over 80 years as a tracer method for studying natural phenomena. More recently a positron emitting radioiso ... Full text Cite

Proposal for the Simultaneous Measurement of the Neutron-Neutron and Neutron-Proton Quasi-Free Scattering Cross Section via the Neutron-Deuteron Breakup Reaction at En = 19 MeV

Journal Article Few-Body Systems · January 1, 2013 In order to confirm or refute the present discrepancy between data and calculation for the neutron-neutron quasi-free scattering cross section in the neutron-deuteron breakup reaction, we describe a new experimental approach currently being pursued at TUNL ... Full text Cite

Imaging corn plants with PhytoPET, a modular PET system for plant biology

Journal Article IEEE Nuclear Science Symposium Conference Record · January 1, 2013 PhytoPET is a modular positron emission tomography (PET) system designed specifically for plant imaging. The PhytoPET design allows flexible arrangements of PET detectors based on individual standalone detector modules built from single Hamamatsu H8500 pos ... Full text Cite

SU-E-T-108: 3D Measurement of Neutron Dose from a Novel Neutron Imaging Technique.

Journal Article Med Phys · June 2012 PURPOSE: We have been developing a fast-neutron spectroscopic technique to quantitatively image the distribution of elements in the body using quasi-monochromatic neutron beams. Previously, we demonstrated the ability of the technique to quantify specific ... Full text Link to item Cite

Photodisintegration cross section of the reaction 4He(γ,n)3He at the giant dipole resonance peak

Journal Article Physical Review C - Nuclear Physics · June 1, 2012 The photodisintegration cross section of 4He into a neutron and helion was measured at incident photon energies of 27.0, 27.5, and 28.0 MeV. A high-pressure 4He-Xe gas scintillator served as target and detector while a pure Xe gas scintillator was used for ... Full text Cite

Cross-section measurements of 2H(n,np)n in symmetric star configurations

Journal Article Physical Review C - Nuclear Physics · May 16, 2012 Cross-section measurements have been made at 16 and 19 MeV in two exit-channel configurations of neutron-deuteron breakup: the space star and coplanar star. In this kinematically complete measurement, the outgoing proton and one of the neutrons were detect ... Full text Cite

PhytoBeta imager: a positron imager for plant biology.

Journal Article Physics in Medicine and Biology · 2012 Link to item Cite

Photodisintegration cross section of the reaction (4)He(γ,p)(3)H between 22 and 30 MeV.

Journal Article Physical review letters · January 2012 The two-body photodisintegration cross section of (4)He into a proton and triton was measured with monoenergetic photon beams in 0.5 MeV energy steps between 22 and 30 MeV. High-pressure (4)He-Xe gas scintillators of various (4)He/Xe ratios served as targe ... Full text Cite

Nuclear physics detector technology applied to plant biology research

Journal Article Nuclear Instruments and Methods in Physics Research A · 2012 Link to item Cite

Proposal for the Simultaneous Measurement of the Neutron-Neutron and Neutron-Proton Quasi-Free Scattering Cross Section via the Neutron-Deuteron Breakup Reaction at E n = 19 MeV

Journal Article Few-Body Systems · 2012 Cite

Asymmetry dependence of nucleon correlations in spherical nuclei extracted from a dispersive-optical-model analysis

Journal Article Physical Review C - Nuclear Physics · June 15, 2011 Neutron elastic-scattering angular distributions were measured at beam energies of 11.9 and 16.9 MeV on Ca40,48 targets. These data plus other elastic-scattering measurements, total and reaction cross-sections measurements, (e,e′p) data, and single-particl ... Full text Cite

Cross-section measurements of neutron-induced reactions on GaAs using monoenergetic beams from 7.5 to 15 MeV

Journal Article Physical Review C - Nuclear Physics · April 28, 2011 Cross-section measurements for neutron-induced reactions on GaAs have been carried out at twelve different neutron energies from 7.5 to 15 MeV using the activation technique. The monoenergetic neutron beams were produced via the H2(d,n)He3 reaction. GaAs s ... Full text Cite

Cross section measurements of neutron induced reactions on GaAs using monoenergetic beams from 7.5 to 15 MeV

Journal Article Journal of Physics: Conference Series · January 1, 2011 Cross section measurements for the neutron induced reactions on GaAs have been carried out at ten different neutron energies from 7.5 to 15 MeV, using the activation technique. The monoenergetic neutron beams were produced via the 2H(d,n)3He reaction, know ... Full text Cite

Measurement of the S01 neutron-neutron effective range in neutron-deuteron breakup

Neutron-neutron quasifree scattering in neutron-deuteron breakup at 10 MeV

Design of an Experiment to Measure ann Using ³ H (γ, pn) n at HIγS

Monte-Carlo Simulation of ³H(γ, pn) n and ³He(γ, pp) n Experiments at HI γs

Neutron-neutron quasifree scattering in nd breakup at 10 MeV

Measurement of the half-life of the T= 12 mirror decay of Ne 19 and its implication on physics beyond the standard model

Neutron-deuteron analyzing power data at En=22.5 MeV

Nuclear physics detector technology applied to plant biology research

Proposal for the Simultaneous Measurement of the Neutron-Neutron and Neutron-Proton Quasi-Free Scattering Cross Section via the Neutron-Deuteron Breakup Reaction at En = 19 MeV

Imaging corn plants with PhytoPET, a modular PET system for plant biology

SU-E-T-108: 3D Measurement of Neutron Dose from a Novel Neutron Imaging Technique.

Photodisintegration cross section of the reaction 4He(γ,n)3He at the giant dipole resonance peak

Cross-section measurements of 2H(n,np)n in symmetric star configurations

PhytoBeta imager: a positron imager for plant biology.

Journal Article Physics in Medicine and Biology · 2012 Link to item Cite

Photodisintegration cross section of the reaction (4)He(γ,p)(3)H between 22 and 30 MeV.

Nuclear physics detector technology applied to plant biology research

Journal Article Nuclear Instruments and Methods in Physics Research A · 2012 Link to item Cite

Proposal for the Simultaneous Measurement of the Neutron-Neutron and Neutron-Proton Quasi-Free Scattering Cross Section via the Neutron-Deuteron Breakup Reaction at E n = 19 MeV

Journal Article Few-Body Systems · 2012 Cite

Asymmetry dependence of nucleon correlations in spherical nuclei extracted from a dispersive-optical-model analysis

Cross-section measurements of neutron-induced reactions on GaAs using monoenergetic beams from 7.5 to 15 MeV

Cross section measurements of neutron induced reactions on GaAs using monoenergetic beams from 7.5 to 15 MeV

Development of PhytoPET: A plant imaging PET system

Journal Article IEEE Nuclear Science Symposium Conference Record · January 1, 2011 The development and initial evaluation of a high-resolution positron emission tomography (PET) system to image the biodistribution of positron emitting tracers in live plants is underway. The positron emitting 11CO2 tracer is used in plant biology research ... Full text Cite

Compact beta particle/positron imager for plant biology

Journal Article IEEE Nuclear Science Symposium Conference Record · December 1, 2010 The 11 CO2 tracer is used to facilitate plant biology research towards optimization of plant productivity, biofuel development and carbon sequestration in biomass. Positron emission tomography (PET) imaging has been used to study carbon transport in live p ... Full text Cite

A feasibility study using radiochromic films for fast neutron 2D passive dosimetry.

Journal Article Phys Med Biol · September 7, 2010 The objective of this paper is threefold: (1) to establish sensitivity of XRQA and EBT radiochromic films to fast neutron exposure; (2) to develop a film response to radiation dose calibration curve and (3) to investigate a two-dimensional (2D) film dosime ... Full text Link to item Cite

Neutron-deuteron analyzing power data at 19.0 MeV

Journal Article Physical Review C - Nuclear Physics · February 23, 2010 Measurements of neutron-deuteron (n-d) analyzing power Ay(θ) at En=19.0 MeV are reported at 16 angles from θc.m.=46.7 to 152.0°. The objective of the experiment is to better characterize the discrepancies between n-d data and the predictions of three-nucle ... Full text Open Access Cite

Positron emission tomography detector development for plant biology

Journal Article IEEE Nuclear Science Symposium Conference Record · December 1, 2009 There are opportunities for the development of new tools to advance plant biology research through the use of radionuclides. Thomas Jefferson National Accelerator Facility, Duke University, West Virginia University and the University of Maryland are collab ... Full text Cite

Cross sections for U238(n,n'γ) and U238(n,2nγ) reactions at incident neutron energies between 5 and 14 MeV

Journal Article Physical Review C - Nuclear Physics · August 6, 2009 Precision measurements of U238(n,n'γ) and U238(n,2nγ) partial cross sections have been performed at Triangle Universities Nuclear Laboratory (TUNL) to improve crucial data needed for testing nuclear reaction models in the actinide mass region. A pulsed and ... Full text Cite

Neutron detection efficiency determinations for the TUNL neutron-neutron and neutron-proton scattering-length measurements

Journal Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment · February 11, 2009 The methods employed and the results obtained from measurements and calculations of the detection efficiency for the neutron detectors used at Triangle Universities Nuclear Laboratory (TUNL) in the simultaneous determination of the 1S0 neutron-neutron and ... Full text Cite

SU‐FF‐T‐436: Comparison of Neutron Doses to a Water Target Exposed to a 10 MeV Neutron Beam: Foil Activation Method Vs. Monte Carlo Simulations

Conference Medical Physics · January 1, 2009 We developed a mouse dosimetry model for neutron beam, and compared the calculated and simulated neutron doses for a water target (mouse) exposed to a 10 MeV neutron beam. We also estimated the longitudinal neutron dose profile for the water target. A wate ... Full text Cite

SU‐FF‐T‐372: Novel Neutron Dosimetry Using Radiochromic Films for 10 MeV Neutrons

Conference Medical Physics · January 1, 2009 The purpose of this paper is to estimate neutron doses using radiochromic XRQA films. Five radiochromic films, placed at varying distances from the neutron source and a water bottle, were exposed to a flux of 10 MeV neutrons produced via the d(d, n)He reac ... Full text Cite

Neutrons from a proton-driven deuterium target as a possible competitor to spallation for nuclear energy applications

Journal Article Nuclear Science and Engineering · January 1, 2009 Measurements are reported on the yield of neutrons from protons in the energy range from 7 to 17 MeV striking a stopping-length target of deuterium gas. This combination of beam and target is being investigated as an alternative to spallation for accelerat ... Full text Cite

Reducing Parasitic Thermal Neutron Absorption in Graphite by 30%

Journal Article Nucl. Science and Eng. · 2009 Cite

Exploring the transport of plant metabolites using positron emitting radiotracers.

Journal Article HFSP journal · August 2008 Short-lived positron-emitting radiotracer techniques provide time-dependent data that are critical for developing models of metabolite transport and resource distribution in plants and their microenvironments. Until recently these techniques were applied t ... Full text Cite

Cross section measurements of the B10(d,n0)C11 reaction below 160 keV

Journal Article Physical Review C - Nuclear Physics · May 27, 2008 New data were taken at the Triangle Universities Nuclear Laboratory to investigate the plausibility of using low energy deuterons and the B10(d,n)C11 reaction as a portable source of 6.3 MeV neutrons. Analysis of the data at and below incident deuteron ene ... Full text Cite

Measurement of the Am241(n,2n) reaction cross section from 7.6 MeV to 14.5 MeV

Journal Article Physical Review C - Nuclear Physics · May 27, 2008 The (n,2n) cross section of the radioactive isotope Am241 (T1/2=432.6 y) has been measured in the incident neutron energy range from 7.6 to 14.5 MeV in steps of a few MeV using the activation technique. Monoenergetic neutron beams were produced via the H2( ... Full text Cite

Neutron-stimulated emission computed tomography of a multi-element phantom.

Journal Article Phys Med Biol · May 7, 2008 This paper describes the implementation of neutron-stimulated emission computed tomography (NSECT) for non-invasive imaging and reconstruction of a multi-element phantom. The experimental apparatus and process for acquisition of multi-spectral projection d ... Full text Link to item Cite

Experimental detection of iron overload in liver through neutron stimulated emission spectroscopy.

Journal Article Physics in medicine and biology · May 2008 Iron overload disorders have been the focus of several quantification studies involving non-invasive imaging modalities. Neutron spectroscopic techniques have demonstrated great potential in detecting iron concentrations within biological tissue. We are de ... Full text Cite

Neutron stimulated emission computed tomography for diagnosis of breast cancer

Journal Article IEEE Transactions on Nuclear Science · January 1, 2008 Neutron stimulated emission computed tomography (NSECT) is being developed as a non-invasive spectroscopic imaging technique to determine element concentrations in the human body. NSECT uses a beam of fast neutrons that scatter inelastically from atomic nu ... Full text Cite

Elemental spectrum of a mouse obtained via neutron stimulation

Journal Article Progress in Biomedical Optics and Imaging - Proceedings of SPIE · October 15, 2007 Several studies have shown that the concentration of certain elements may be a disease indicator. We are developing a spectroscopic imaging technique, Neutron Stimulated Emission Computed Tomography (NSECT), to non-invasively measure and image elemental co ... Full text Cite

Design and development of a high-energy gamma camera for use with NSECT imaging: Feasibility for breast imaging

Journal Article IEEE Transactions on Nuclear Science · October 1, 2007 A new spectroscopic imaging technique, Neutron Stimulated Emission Computed Tomography (NSECT), is currently being developed to non-invasively and non-destructively measure and image elemental concentrations within the body. NSECT has potential for use in ... Full text Cite

Performance Characterization of a Miniature, High Sensitivity Gamma Ray Camera

Journal Article IEEE Transactions on Nuclear Science · October 2007 Full text Cite

Pulsed and monoenergetic beams for neutron cross-section measurements using activation and scattering techniques at Triangle Universities Nuclear Laboratory

Journal Article Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms · August 1, 2007 In support of the Stewardship Science Academic Alliances initiative, an experimental program has been developed at Triangle Universities Nuclear Laboratory (TUNL) to measure (n,xn) cross-sections with both in-beam and activation techniques with the goal of ... Full text Cite

Neutron stimulated emission computed tomography: Background corrections

Journal Article Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms · January 1, 2007 Neutron stimulated emission computed tomography (NSECT) is an imaging technique that provides an in-vivo tomographic spectroscopic image of the distribution of elements in a body. To achieve this, a neutron beam illuminates the body. Nuclei in the body alo ... Full text Cite

Neutron capture and (n,2n) measurements on ²⁴¹Am

Conference ND2007 · 2007 Full text Cite

Introduction to neutron stimulated emission computed tomography.

Journal Article Phys Med Biol · July 21, 2006 Neutron stimulated emission computed tomography (NSECT) is presented as a new technique for in vivo tomographic spectroscopic imaging. A full implementation of NSECT is intended to provide an elemental spectrum of the body or part of the body being interro ... Full text Link to item Cite

Calibration of a neutron polarimeter in the 0.2-1.1 GeV region

Journal Article Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment · February 15, 2006 We measured the analyzing power and the efficiency of a neutron polarimeter at the Saturne National Laboratory in France with central energies of the neutron beam of 261,533,752,922, and 1057 MeV. This polarimeter was a prototype designed to measure GEn, t ... Full text Cite

Astrophysical S factor for the Li7(d,n0)Be8 and Li7(d,n1)Be8 reactions

Journal Article Physical Review C - Nuclear Physics · January 1, 2006 The absolute astrophysical S factor and cross section for the Li7(d,n0)Be8 and Li7(d,n1)Be8 reactions have been determined using deuteron beams with energies between 45 and 80 keV. The slope of the S factor is consistent with zero in the n0 case but is sli ... Full text Cite

Neutron-deuteron breakup experiment at En=13MeV: Determination of the 1S0 neutron-neutron scattering length ann

Journal Article Physical Review C - Nuclear Physics · January 1, 2006 We report on results of a kinematically complete neutron-deuteron breakup experiment performed at Triangle Universities Nuclear Laboratory using an En=13 MeV incident neutron beam. The 1S0 neutron-neutron scattering length ann has been determined for four ... Full text Cite

Non-invasive estimation of potassium (39K) in Bovine Liver using Neutron Stimulated Emission Computed Tomography (NSECT)

Journal Article IEEE Nuclear Science Symposium Conference Record · January 1, 2006 Neutron stimulated emission computed tomography (NSECT) is being developed as a non-invasive technique to measure element concentration in in-vivo tissue at molecular levels. We have developed a system that performs this task using an incident neutron beam ... Full text Cite

Design and construction of a prototype rotation modulation collimator for near-field high-energy spectroscopic gamma imaging

Journal Article IEEE Nuclear Science Symposium Conference Record · January 1, 2006 Neutron Stimulated Emission Computed Tomography (NSECT) is being developed for in vivo measurement of the concentration and location of biologically relevant elements. NSECT is a spectroscopic imaging technique whereby the body is illuminated via high-ener ... Full text Cite

The Li7(d→,n0)Be8 and Li7(d→,n1)Be8 reactions below 160 keV

Journal Article Physical Review C - Nuclear Physics · January 1, 2006 The polarization observables have been determined for the Li7(d→,n0)Be8 and Li7(d→,n1)Be8 reactions at beam energies between 80 and 160 keV. A Transition Matrix Element (TME) analysis revealed unique, dominant p-wave solutions for both neutron channels. Th ... Full text Cite

Development of a High-Energy Gamma Camera for use with NSECT Imaging of the Breast

Conference 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6 · January 1, 2006 Link to item Cite

Neutron Spectroscopy of Mouse Using Neutron Stimulated Emission Computed Tomography (NSECT)

Conference 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6 · January 1, 2006 Link to item Cite

Neutron Stimulated Emission Computed Tomography (NSECT) for Early Detection of Breast Cancer

Conference 2006 IEEE Nuclear Science Symposium Conference Record · 2006 Full text Cite

Non-invasive quantification of iron⁵⁶Fe in beef liver using neutron stimulated emission computed tomography

Journal Article IEEE Nuclear Science Symposium Conference Record · December 1, 2005 Neutron spectroscopy is being developed as a noninvasive tool to measure element concentration in the body at molecular levels. We are developing a neutron stimulated emission computed tomography (NSECT) system to identify element concentrations in tissue, ... Full text Cite

Measurements of Ay(θ) for C12(n,n)C12 from En=2.2 to 8.5 MeV

Journal Article Physical Review C - Nuclear Physics · January 1, 2005 The analyzing power Ay(θ) for neutron elastic scattering from C12 has been measured for 33 neutron energies between En=2.2 and 8.5 MeV in the angular range from 25° to 145° in the laboratory system. The primary motivation for these measurements is the need ... Full text Cite

Neutron stimulated emission computed tomography of stable isotopes

Journal Article Proceedings of SPIE - The International Society for Optical Engineering · July 5, 2004 Here we report on the development of a new molecular imaging technique using inelastic scattering of fast neutrons. Earlier studies demonstrated a significant difference in trace element concentrations between benign and malignant tissue for several cancer ... Full text Cite

Accelerator-driven waste transmutation experiment.

Conference HEALTH PHYSICS · June 1, 2003 Link to item Cite

Electromagnetic effects and the long-standing three-nucleon analyzing power puzzle

Journal Article Modern Physics Letters A · February 28, 2003 New results for the neutron-deuteron analyzing power Ay (θ) at En = 1.2 and 1.9 MeV and their comparison to proton-deuteron data reveal a sizeable and unexpected difference which increases with decreasing center-of-mass energy. This finding calls for the t ... Full text Cite

A new twist to the long-standing three-nucleon analyzing power puzzle

Journal Article Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics · January 16, 2003 New results for the neutron-deuteron analyzing power Ay(θ) at En = 1.2 and 1.9 MeV and their comparison to proton-deuteron data reveal a sizeable and unexpected difference which increases with decreasing center-of-mass energy. This finding calls for the th ... Full text Cite

The space-star anomaly in nd breakup at 25 MeV

Journal Article Nuclear Physics A · March 12, 2001 Full text Cite

Recent high-accuracy measurements of the S-1(0) neutron-neutron scattering length

Journal Article FEW-BODY PROBLEMS IN PHYSICS '99 · January 1, 2000 Link to item Cite

A new measurement of the 1S0 neutron-neutron scattering length using the neutron-proton scattering length as a standard

Journal Article Physical Review Letters · January 1, 1999 The present paper reports high-accuracy cross-section data for the 2H(n, nnp) reaction in the neutron-proton (np) and neutron-neutron (nn) final-state-interaction (FSI) regions at an incident mean neutron energy of 13.0 MeV. These data were analyzed with r ... Full text Cite