scholarly journals Precision measurements on oxygen formation in stellar helium burning with gamma-ray beams and a Time Projection Chamber

2021 ◽  
Author(s):  
Robin Smith ◽  
Moshe Gai ◽  
Sarah Stern ◽  
Deran Schweitzer ◽  
Mohammad Ahmed
Keyword(s):  
Time Projection Chamber ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Angular Distributions ◽  
Helium Burning ◽  
Low Energies ◽  
Important Input ◽  
Novel Method ◽  
Time Projection ◽  
First Time

Abstract Stellar Evolution theory relies on our knowledge of nuclear reactions, with the carbon/oxygen (C/O) ratio, at the end of helium burning, being the single most important input. However, the C/O ratio is still not known with sufficient accuracy, due to large uncertainties in the cross section for the fusion of helium with 12C to form 16O, denoted as the 12C(α,γ)16O reaction. We present initial results at moderately low energies using a novel method, which is significantly different from the experimental efforts of the past four decades. Precise angular distributions of the 12C(α,γ)16O reaction were obtained by measuring the inverse 16O(γ,α)12C reaction with gamma-beams and a Time Projection Chamber detector. These allowed us to measure, for the first time, the interference angle of the l = 1 and 2 partial waves contributing to this reaction (φ12), which agrees with predictions based on the unitarity of the scattering matrix.

scholarly journals Precision measurements on oxygen formation in stellar helium burning with gamma-ray beams and a Time Projection Chamber

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
R. Smith ◽  
M. Gai ◽  
S. R. Stern ◽  
D. K. Schweitzer ◽  
M. W. Ahmed
Keyword(s):  
Cross Section ◽  
Time Projection Chamber ◽  
Gamma Ray ◽  
Reaction Cross ◽  
Total Reaction Cross Section ◽  
Angular Distributions ◽  
Helium Burning ◽  
The Past ◽  
Time Projection

AbstractThe carbon/oxygen (C/O) ratio at the end of stellar helium burning is the single most important nuclear input to stellar evolution theory. However, it is not known with sufficient accuracy, due to large uncertainties in the cross-section for the fusion of helium with 12C to form 16O, denoted as 12C(α, γ)16O. Here we present results based on a method that is significantly different from the experimental efforts of the past four decades. With data measured inside one detector and with vanishingly small background, angular distributions of the 12C(α, γ)16O reaction were obtained by measuring the inverse 16O(γ, α)12C reaction with gamma-beams and a Time Projection Chamber (TPC) detector. We agree with current world data for the total reaction cross-section and further evidence the strength of our method with accurate angular distributions measured over the 1− resonance at Ecm ~ 2.4 MeV. Our technique promises to yield results that will surpass the quality of the currently available data.

scholarly journals On the Experimental Investigation of the Angular Distributions in the Reaction 112Cd(p,γ)113In

2019 ◽  
Vol 26 ◽  
pp. 188
Author(s):  
A. Zyriliou ◽  
A. Khaliel ◽  
T. J. Mertzimekis
Keyword(s):  
Cross Sections ◽  
Nuclear Physics ◽  
Gamma Ray ◽  
Reaction Cross ◽  
Angular Distributions ◽  
Special Focus ◽  
Tandem Accelerator ◽  
Section Data ◽  
Hpge Detectors ◽  
Low Energies

Some of the mid–weight nuclei lie in the region of the isotopic chart where the astrophysical p-process has a prominent role in the nucleosynthetic scenarios. Experimentally deduced reaction cross section data can provide stringent tests for the astrophysical models, especially at low energies. In this framework, the reaction 112Cd(p,γ)113In has been studied experimentally at four proton beam energies 2.8 ≤ Ep≤ 3.4 MeV, partly inside the astrophysically interesting Gamow window. Proton beams were provided by the 5.5 MV T11 Van de Graaff Tandem Accelerator of the Institute of Nuclear Physics of the National Center for Scientific Research (NCSR) “Demokritos”. In–beam spectroscopy was carried out with an array of four HPGe detectors sitting on a rotating table. In total, eight (8) different angles were used to record gamma–ray spectra. Special focus was given on constructing the angular distribution of each gamma–ray feeding the ground state of 113In directly, so as to determine the reaction cross sections from the in–beam data, exclusively. The resulting cross sections were compared to Hauser–Feshbach calculations using the code TALYS v1.9.

scholarly journals Pairing effects on neutron elastic scattering at low-energies

2020 ◽  
Vol 129 (1B) ◽  
pp. 57-61
Author(s):  
N. Hoang Tung ◽  
T. Dieu Thuy ◽  
D. Quang Tam ◽  
T. Ngoc Quynh Tran ◽  
T. V. Nhan Hao
Keyword(s):  
Elastic Scattering ◽  
Ground State ◽  
Open Shell ◽  
Angular Distributions ◽  
Microscopic Calculation ◽  
Energy Neutron ◽  
Low Energies ◽  
Pairing Correlations ◽  
Vibration Coupling ◽  
First Time

For the first time, a realistic microscopic calculation for low-energy neutron-nucleus elastic scattering off open-shell nuclei is carried out within the framework of particle-vibration coupling (PVC). In this study, the pairing correlations of the ground state are taken into account. The dependence of the angular distributions on the pairing gaps is discussed.

scholarly journals Sealed operation, and circulation and purification of gas in the HARPO TPC

2018 ◽  
Vol 174 ◽  
pp. 05002 ◽  
Author(s):  
M. Frotin ◽  
P. Gros ◽  
D. Attié ◽  
D. Bernard ◽  
V. Dauvois ◽  
...  
Keyword(s):  
Time Projection Chamber ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Complete Recovery ◽  
Space Mission ◽  
Mode Operation ◽  
Future Space ◽  
Purification System ◽  
Gas Circulation ◽  
Time Projection

HARPO is a time projection chamber (TPC) demonstrator of a gamma-ray telescope and polarimeter in the MeV-GeV range, for a future space mission. We present the evolution of the TPC performance over a five month sealed-mode operation, by the analysis of cosmic-ray data, followed by the fast and complete recovery of the initial gas properties using a lightweight gas circulation and purification system.

scholarly journals Pairing effects on neutron elastic scattering at low-energies

2020 ◽  
Vol 129 (1B) ◽  
Author(s):  
Trần Viết Nhân Hào ◽  
Hoàng Tùng Nguyễn ◽  
Diệu Thùy Trần ◽  
Quang Tâm Đỗ ◽  
Ngọc Quỳnh Trân Trần ◽  
...  
Keyword(s):  
Elastic Scattering ◽  
Ground State ◽  
Open Shell ◽  
Angular Distributions ◽  
Microscopic Calculation ◽  
Energy Neutron ◽  
Low Energies ◽  
Pairing Correlations ◽  
Vibration Coupling ◽  
First Time

For the first time, a realistic microscopic calculation for low-energy neutron-nucleus elastic scattering off open-shell nuclei is carried out within the framework of particle-vibration coupling (PVC). In this study, the pairing correlations of the ground state are taken into account. The dependence of the angular distributions on the pairing gaps have been discussed.

scholarly journals Activation cross section data of deuteron induced nuclear reactions on rubidium up to 50 MeV

2021 ◽  
Vol 57 (1) ◽  
Author(s):  
Ferenc Tárkányi ◽  
Alex Hermanne ◽  
Ferenc Ditrói ◽  
Sándor Takács ◽  
Anatolij V. Ignatyuk ◽  
...  
Keyword(s):  
Cross Sections ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Thick Target ◽  
Gamma Ray Spectrometry ◽  
Activation Cross Section ◽  
Experimental Database ◽  
Practical Applications ◽  
Section Data ◽  
First Time

AbstractActivation cross sections of the $$^{\mathrm {nat}}\hbox {Rb (d,xn)}^{87\mathrm {m,85m,85g,83,82}}\hbox {Sr}$$ nat Rb (d,xn) 87 m , 85 m , 85 g , 83 , 82 Sr , $$^{\mathrm {nat}}\hbox {Rb(d,x)}^{\mathrm {86,84,83,82m}}\hbox {Rb}$$ nat Rb(d,x) 86 , 84 , 83 , 82 m Rb and $$^{\mathrm {nat}}\hbox {Rb(d,x)}^{85\mathrm {m}}\hbox {Kr}$$ nat Rb(d,x) 85 m Kr nuclear reactions have been measured for the first time through an activation method combining the stacked foil irradiation technique and gamma-ray spectrometry. The provided cross sections from the present investigation are all new, in such a way contribute to the completeness of the experimental database. The experimental cross sections were compared with the theoretical prediction in the TENDL-2019 TALYS based library and with our calculation using ALICE-D and EMPIRE-D model codes in order the improve their predictivity. Thick target production yields were calculated form the new cross sections for all investigated radioisotopes. Practical applications of the results are shortly discussed.

scholarly journals High resolution gamma ray detection in a dual phase xenon time projection chamber

2014 ◽  
Vol 9 (04) ◽  
pp. P04014-P04014 ◽  
Author(s):  
Q Lin ◽  
Y Wei ◽  
J Bao ◽  
J Hu ◽  
X Li ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Projection Chamber ◽  
Gamma Ray ◽  
Dual Phase ◽  
Time Projection ◽  
High Resolution Gamma

Study of negative parity levels in 63Cu

1980 ◽  
Vol 58 (4) ◽  
pp. 472-480 ◽  
Author(s):  
R.G. Kulkarni ◽  
D. P. Navalkele
Keyword(s):  
Gamma Ray ◽  
Transition Probabilities ◽  
Negative Parity ◽  
Angular Distributions ◽  
Core Excitation ◽  
Model Calculations ◽  
Mixing Ratios ◽  
Reduced Transition Probabilities ◽  
Excitation Model ◽  
First Time

Low-lying negative parity levels in 63Cu were Coulomb excited with 3.25 to 4.25 MeV protons to test the weak coupling core-excitation model. A Ge(Li) detector was used to measure the gamma-ray yields. The 1412, 1547, and 1861 keV levels in 63Cu were Coulomb excited for the first time. Gamma-ray angular distributions were measured at 4.25 MeV proton energy in deducing multipole mixing ratios and spin values. The E2 and M1 reduced transition probabilities were determined for the six states. The 669.6, 962, 1327, and 1547 keV levels have properties consistent with the interpretation of coupling a 2p3/2 proton to the first 2+core state. The present results were compared with the available particle–core and particle–phonon model calculations.

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