Pub Date : 2021-03-04DOI: 10.1103/PHYSREVC.103.L031302
J. Chen, S. Wang, H. Fortune, J. Lou, Y. Ye, Z. Li, N. Michel, J. G. Li, C. Yuan, Y. Ge, Q. Li, H. Hua, D. Jiang, X. Yang, D. Pang, F. Xu, W. Zuo, J. Pei, J. Li, W. Jiang, Y. Sun, H. Zang, N. Aoi, H. Ong, E. Ideguchi, Y. Ayyad, K. Hatanaka, D. T. Tran, D. Bazin, J. Lee, Y. Zhang, J. Wu, H. Liu, C. Wen, T. Yamamoto, M. Tanaka, T. Suzuki
A resonant state at $3.21^{+0.12}_{-0.04}$,MeV, located just above the one-neutron separation threshold, was observed for the first time in $^{12}$Be from the $^{11}$Be,$(d,p)^{12}$Be one-neutron transfer reaction in inverse kinematics. This state is assigned a spin-parity of $0^-$, according to the distorted-wave Born approximation (DWBA) and decay-width analysis. Gamow coupled-channel (GCC) and Gamow shell-model (GSM) calculations show the importance of the continuum-coupling, which dramatically influences the excitation energy and ordering of low-lying states. Various exotic structures associated with cross-shell intruding configurations in $^{12}$Be and in its isotonic nucleus $^{11}$Li are comparably discussed.
{"title":"Observation of the near-threshold intruder \u00000−\u0000 resonance in \u0000Be12","authors":"J. Chen, S. Wang, H. Fortune, J. Lou, Y. Ye, Z. Li, N. Michel, J. G. Li, C. Yuan, Y. Ge, Q. Li, H. Hua, D. Jiang, X. Yang, D. Pang, F. Xu, W. Zuo, J. Pei, J. Li, W. Jiang, Y. Sun, H. Zang, N. Aoi, H. Ong, E. Ideguchi, Y. Ayyad, K. Hatanaka, D. T. Tran, D. Bazin, J. Lee, Y. Zhang, J. Wu, H. Liu, C. Wen, T. Yamamoto, M. Tanaka, T. Suzuki","doi":"10.1103/PHYSREVC.103.L031302","DOIUrl":"https://doi.org/10.1103/PHYSREVC.103.L031302","url":null,"abstract":"A resonant state at $3.21^{+0.12}_{-0.04}$,MeV, located just above the one-neutron separation threshold, was observed for the first time in $^{12}$Be from the $^{11}$Be,$(d,p)^{12}$Be one-neutron transfer reaction in inverse kinematics. This state is assigned a spin-parity of $0^-$, according to the distorted-wave Born approximation (DWBA) and decay-width analysis. Gamow coupled-channel (GCC) and Gamow shell-model (GSM) calculations show the importance of the continuum-coupling, which dramatically influences the excitation energy and ordering of low-lying states. Various exotic structures associated with cross-shell intruding configurations in $^{12}$Be and in its isotonic nucleus $^{11}$Li are comparably discussed.","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77405992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-21DOI: 10.1016/j.nuclphysa.2021.122248
A. Vodin, O. S. Deiev, V. Korda, I. S. Timchenko, Š. Olejník, N. I. Aizatsky, A. S. Kachan, L. P. Korda, E. Kuplennikov, V. Kushnir, V. Mitrochenko, S. K. L. O. N. Physics, Technology, National Academy of Sciences of Ukraine, Kharkov, Ukraine, Institute of Electrophysics, Radiation Technologies
{"title":"Photoneutron reactions on $^{text{93}}$Nb at $E_{gamma text{max}}$=33-93 MeV.","authors":"A. Vodin, O. S. Deiev, V. Korda, I. S. Timchenko, Š. Olejník, N. I. Aizatsky, A. S. Kachan, L. P. Korda, E. Kuplennikov, V. Kushnir, V. Mitrochenko, S. K. L. O. N. Physics, Technology, National Academy of Sciences of Ukraine, Kharkov, Ukraine, Institute of Electrophysics, Radiation Technologies","doi":"10.1016/j.nuclphysa.2021.122248","DOIUrl":"https://doi.org/10.1016/j.nuclphysa.2021.122248","url":null,"abstract":"","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80161051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-02DOI: 10.1103/PHYSREVD.103.052007
J. Collar
Experiments looking for a lepton flavor-violating decay $mu^{+}!!rightarrow !e^{+} X^{0}$ are reviewed in light of present-day germanium detector technology, with an eye on scenarios where a long-lived, slow-moving massive boson $X^{0}$ might have a cosmological impact. A broad swath of interesting, unexplored parameter space very close to the kinematic limit of the decay is found to be within the reach of a new proposed search. A number of possible roles for $X^{0}$ in past and present epochs can be investigated.
{"title":"Search for a cosmologically relevant boson in muon decay","authors":"J. Collar","doi":"10.1103/PHYSREVD.103.052007","DOIUrl":"https://doi.org/10.1103/PHYSREVD.103.052007","url":null,"abstract":"Experiments looking for a lepton flavor-violating decay $mu^{+}!!rightarrow !e^{+} X^{0}$ are reviewed in light of present-day germanium detector technology, with an eye on scenarios where a long-lived, slow-moving massive boson $X^{0}$ might have a cosmological impact. A broad swath of interesting, unexplored parameter space very close to the kinematic limit of the decay is found to be within the reach of a new proposed search. A number of possible roles for $X^{0}$ in past and present epochs can be investigated.","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85223185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-26DOI: 10.1103/PHYSREVC.103.015807
J. Riley, A. Laird, N. de Séréville, A. Parikh, S. Fox, F. Hammache, I. Stefan, P. Adsley, M. Assi'e, B. Bastin, F. Boulay, A. Coc, S. Franchoo, R. Garg, S. Gillespie, V. Guimarães, C. Hamadache, N. Hubbard, J. Kiener, A. Lefebvre‐Schuhl, F. Santos, A. Remadi, L. Perrot, D. Suzuki, G. Verde, V. Tatischeff, M. Williams
Classical novae result from thermonuclear explosions producing several $gamma$-ray emitters which are prime targets for satellites observing in the MeV range. The early 511 keV gamma-ray emission depends critically on the $^{18}$F(p,$alpha$)$^{15}$O reaction rate which, despite many experimental and theoretical efforts, still remains uncertain. One of the main uncertainties in the $^{18}$F(p,$alpha$)$^{15}$O reaction rate is the contribution in the Gamow window of interference between sub-threshold $^{19}$Ne states and known broad states at higher energies. Therefore the goal of this work is to clarify the existence and the nature of these sub-threshold states. States in the $^{19}$Ne compound nucleus were studied at the Tandem-ALTO facility using the $^{19}$F($^3$He,t)$^{19}$Ne charge exchange reaction. Tritons were detected with an Enge Split-pole spectrometer while decaying protons or $alpha$-particles from unbound $^{19}$Ne states were collected, in coincidence, with a double-sided silicon strip detector array. Angular correlations were extracted and constraints on the spin and parity of decaying states established. The coincidence yield at $E_x$ = 6.29 MeV was observed to be high spin, supporting the conclusion that it is indeed a doublet consisting of high spin and low spin components. Evidence for a broad, low spin state was observed around 6 MeV. Branching ratios were extracted for several states above the proton threshold and were found to be consistent with the literature. R-matrix calculations show the relative contribution of sub-threshold states to the astrophysically important energy region above the proton threshold. The levels schemes of $^{19}$Ne and $^{19}$F are still not sufficiently well known and further studies of the analogue assignments are needed. The tentative broad state at 6 MeV may only play a role if the reduced proton width is large.
{"title":"Sub-threshold states in \u0000Ne19\u0000 relevant to \u0000F18(p,α)O15","authors":"J. Riley, A. Laird, N. de Séréville, A. Parikh, S. Fox, F. Hammache, I. Stefan, P. Adsley, M. Assi'e, B. Bastin, F. Boulay, A. Coc, S. Franchoo, R. Garg, S. Gillespie, V. Guimarães, C. Hamadache, N. Hubbard, J. Kiener, A. Lefebvre‐Schuhl, F. Santos, A. Remadi, L. Perrot, D. Suzuki, G. Verde, V. Tatischeff, M. Williams","doi":"10.1103/PHYSREVC.103.015807","DOIUrl":"https://doi.org/10.1103/PHYSREVC.103.015807","url":null,"abstract":"Classical novae result from thermonuclear explosions producing several $gamma$-ray emitters which are prime targets for satellites observing in the MeV range. The early 511 keV gamma-ray emission depends critically on the $^{18}$F(p,$alpha$)$^{15}$O reaction rate which, despite many experimental and theoretical efforts, still remains uncertain. One of the main uncertainties in the $^{18}$F(p,$alpha$)$^{15}$O reaction rate is the contribution in the Gamow window of interference between sub-threshold $^{19}$Ne states and known broad states at higher energies. Therefore the goal of this work is to clarify the existence and the nature of these sub-threshold states. States in the $^{19}$Ne compound nucleus were studied at the Tandem-ALTO facility using the $^{19}$F($^3$He,t)$^{19}$Ne charge exchange reaction. Tritons were detected with an Enge Split-pole spectrometer while decaying protons or $alpha$-particles from unbound $^{19}$Ne states were collected, in coincidence, with a double-sided silicon strip detector array. Angular correlations were extracted and constraints on the spin and parity of decaying states established. The coincidence yield at $E_x$ = 6.29 MeV was observed to be high spin, supporting the conclusion that it is indeed a doublet consisting of high spin and low spin components. Evidence for a broad, low spin state was observed around 6 MeV. Branching ratios were extracted for several states above the proton threshold and were found to be consistent with the literature. R-matrix calculations show the relative contribution of sub-threshold states to the astrophysically important energy region above the proton threshold. The levels schemes of $^{19}$Ne and $^{19}$F are still not sufficiently well known and further studies of the analogue assignments are needed. The tentative broad state at 6 MeV may only play a role if the reduced proton width is large.","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80856057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We overview recent jet measurements in pp and Pb-Pb collisions with the ALICE detector. ALICE reconstructs jets at midrapidity using the anti-$k_{mathrm{T}}$ algorithm, including both charged particle jets from the ALICE tracking detectors, and full jets from the combination of the ALICE electromagnetic calorimeter with the tracking system. We focus on inclusive and semi-inclusive jet measurements as well as jet substructure measurements, including a variety of groomed and ungroomed observables. In pp collisions, these results test pQCD techniques at $p_{mathrm{T,;jet}}<140$ GeV$/c$ in a low pileup environment, and can constrain models of non-perturbative effects. In Pb-Pb collisions, these measurements test models of jet quenching in the quark-gluon plasma, and can be used to constrain the properties of high temperature QCD matter.
{"title":"Overview of the latest jet physics results from ALICE","authors":"J. Mulligan","doi":"10.22323/1.390.0556","DOIUrl":"https://doi.org/10.22323/1.390.0556","url":null,"abstract":"We overview recent jet measurements in pp and Pb-Pb collisions with the ALICE detector. ALICE reconstructs jets at midrapidity using the anti-$k_{mathrm{T}}$ algorithm, including both charged particle jets from the ALICE tracking detectors, and full jets from the combination of the ALICE electromagnetic calorimeter with the tracking system. We focus on inclusive and semi-inclusive jet measurements as well as jet substructure measurements, including a variety of groomed and ungroomed observables. In pp collisions, these results test pQCD techniques at $p_{mathrm{T,;jet}}<140$ GeV$/c$ in a low pileup environment, and can constrain models of non-perturbative effects. In Pb-Pb collisions, these measurements test models of jet quenching in the quark-gluon plasma, and can be used to constrain the properties of high temperature QCD matter.","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82756189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-26DOI: 10.1103/PHYSREVD.103.074010
A. Serebrov, M. Chaikovskii, G. Klyushnikov, O. Zherebtsov, A. Chechkin
All results of the neutron lifetime measurements performed in the last 20 years with the UCN storage method are in a good agreement. These results are also consistent with the latest most accurate measurements of the neutron decay asymmetry within the Standard Model. However, there is a significant discrepancy at $3.6sigma$ (1% of the decay probability) level between the averaged result of the storage method experiments and the most precise value obtained with the beam method. This article addresses the possible causes of that discrepancy. We focused on finding the spectrum of possible systematic corrections in the beam experiment. Four separate sources of the systematic errors which had not been properly addressed previously were considered. Two of those sources are related with the motion of protons in an electromagnetic field and the elastic scattering by the residual gas. These problems are associated with the geometrical configuration of the setup and the proton detector size. The Monte-Carlo simulation shows that these effects are negligible and do not affect measurement results. The third error concerns proton loss in the dead layer of the detector. It is shown that this correction requires a more detailed analysis than that given in the papers describing the beam measurement method. The fourth source of the systematic error is the charge exchange process on the residual gas. The influence of the residual gas was neglected in the beam method experiment. We present arguments that careful analysis of this issue is necessary since the proposed proton losses correction decreases the measured lifetime bringing it closer to the storage method results. Spectrum of possible corrections concerning this issue is investigated and it is shown that for the precise result, it is necessary to directly measure the concentration and composition of the residual gas inside the proton trap.
{"title":"Search for explanation of the neutron lifetime anomaly","authors":"A. Serebrov, M. Chaikovskii, G. Klyushnikov, O. Zherebtsov, A. Chechkin","doi":"10.1103/PHYSREVD.103.074010","DOIUrl":"https://doi.org/10.1103/PHYSREVD.103.074010","url":null,"abstract":"All results of the neutron lifetime measurements performed in the last 20 years with the UCN storage method are in a good agreement. These results are also consistent with the latest most accurate measurements of the neutron decay asymmetry within the Standard Model. However, there is a significant discrepancy at $3.6sigma$ (1% of the decay probability) level between the averaged result of the storage method experiments and the most precise value obtained with the beam method. This article addresses the possible causes of that discrepancy. We focused on finding the spectrum of possible systematic corrections in the beam experiment. Four separate sources of the systematic errors which had not been properly addressed previously were considered. Two of those sources are related with the motion of protons in an electromagnetic field and the elastic scattering by the residual gas. These problems are associated with the geometrical configuration of the setup and the proton detector size. The Monte-Carlo simulation shows that these effects are negligible and do not affect measurement results. The third error concerns proton loss in the dead layer of the detector. It is shown that this correction requires a more detailed analysis than that given in the papers describing the beam measurement method. The fourth source of the systematic error is the charge exchange process on the residual gas. The influence of the residual gas was neglected in the beam method experiment. We present arguments that careful analysis of this issue is necessary since the proposed proton losses correction decreases the measured lifetime bringing it closer to the storage method results. Spectrum of possible corrections concerning this issue is investigated and it is shown that for the precise result, it is necessary to directly measure the concentration and composition of the residual gas inside the proton trap.","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85575079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Antinuclei are considered to be one of the most promising probes in the indirect search for dark matter (DM) annihilation in space. However, in light of recent results on the production of light antinuclei in pp collisions at the LHC, an abundant production of light (anti)nuclei is also expected from Standard Model (SM) collisions of primary cosmic rays with the interstellar medium. Hence further precise measurements are required to constrain the production models of antinuclei in SM collisions to be sensitive to additional DM annihilation events. The most recent results of the ALICE collaboration on the production of antideuterons ($overline{mathrm{d}}$) and antihelium-3 ($^3overline{text{He}}$) in proton-proton (pp) and proton-lead (p--Pb) collisions are shown. These results provide valuable input for state-of-the-art calculations of the production models currently used to estimate the SM background to DM searches.
{"title":"Understanding the background in dark matter searches by studying antinucleosynthesis in the laboratory with ALICE","authors":"S. Hornung","doi":"10.22323/1.390.0634","DOIUrl":"https://doi.org/10.22323/1.390.0634","url":null,"abstract":"Antinuclei are considered to be one of the most promising probes in the indirect search for dark matter (DM) annihilation in space. However, in light of recent results on the production of light antinuclei in pp collisions at the LHC, an abundant production of light (anti)nuclei is also expected from Standard Model (SM) collisions of primary cosmic rays with the interstellar medium. Hence further precise measurements are required to constrain the production models of antinuclei in SM collisions to be sensitive to additional DM annihilation events. The most recent results of the ALICE collaboration on the production of antideuterons ($overline{mathrm{d}}$) and antihelium-3 ($^3overline{text{He}}$) in proton-proton (pp) and proton-lead (p--Pb) collisions are shown. These results provide valuable input for state-of-the-art calculations of the production models currently used to estimate the SM background to DM searches.","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76741201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-07DOI: 10.1103/PhysRevC.102.054325
A. MacLean, A. Laffoley, C. Svensson, G. Ball, J. Leslie, C. Andreoiu, A. Babu, S. Bhattacharjee, H. Bidaman, V. Bildstein, C. Burbadge, M. Bowry, C. Cheng, D. Cross, A. Diaz-Varela, I. Dillmann, M. Dunlop, R. Dunlop, L. Evitts, P. Finlay, S. Gillespie, A. Garnsworthy, P. Garrett, E. Gopaul, C. Griffin, G. Grinyer, G. Hackman, J. Henderson, B. Jigmeddorj, K. Leach, E. Kassanda, J. McAfee, M. Moukaddam, C. Natzke, S. Nittala, B. Olaizola, J. Park, C. Paxman, J. Pore, C. Porzio, A. Radich, P. Ruotsalainen, Y. Saito, S. Sharma, J. Smallcombe, J. Smith, R. Sultana, J. Turko, J. Williams, D. Yates, T. Zidar
A high-precision branching ratio measurement for the superallowed Fermi $beta^{+}$ emitter $^{62}$Ga was performed with the Gamma-Ray Infrastructure for Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility at TRIUMF. The high efficiency of the GRIFFIN spectrometer allowed 63 $gamma$-ray transitions, with intensities down to $approx$1 part per million (ppm) per $^{62}$Ga $beta^{+}$ decay, to be placed in the level scheme of the daughter nucleus $^{62}$Zn, establishing the superallowed $beta$ branching ratio for $^{62}$Ga decay to be 99.8577$^{+0.0023}_{-0.0029}%$, a factor of 4 more precise than the previous world average. For several cascades, $gamma-gamma$ angular correlation measurements were performed to assign spins and/or determine the mixing ratios of transitions. In particular, the spin of the 2.342 MeV excited state in the daughter nucleus $^{62}$Zn was definitively assigned as $J = 0$. This assignment resolves a discrepancy between previous measurements and has important implications for the isospin symmetry breaking correction, $delta_{C1}$, in $^{62}$Ga superallowed Fermi $beta$ decay.
{"title":"High-precision branching ratio measurement and spin assignment implications for \u0000Ga62\u0000 superallowed \u0000β\u0000 decay","authors":"A. MacLean, A. Laffoley, C. Svensson, G. Ball, J. Leslie, C. Andreoiu, A. Babu, S. Bhattacharjee, H. Bidaman, V. Bildstein, C. Burbadge, M. Bowry, C. Cheng, D. Cross, A. Diaz-Varela, I. Dillmann, M. Dunlop, R. Dunlop, L. Evitts, P. Finlay, S. Gillespie, A. Garnsworthy, P. Garrett, E. Gopaul, C. Griffin, G. Grinyer, G. Hackman, J. Henderson, B. Jigmeddorj, K. Leach, E. Kassanda, J. McAfee, M. Moukaddam, C. Natzke, S. Nittala, B. Olaizola, J. Park, C. Paxman, J. Pore, C. Porzio, A. Radich, P. Ruotsalainen, Y. Saito, S. Sharma, J. Smallcombe, J. Smith, R. Sultana, J. Turko, J. Williams, D. Yates, T. Zidar","doi":"10.1103/PhysRevC.102.054325","DOIUrl":"https://doi.org/10.1103/PhysRevC.102.054325","url":null,"abstract":"A high-precision branching ratio measurement for the superallowed Fermi $beta^{+}$ emitter $^{62}$Ga was performed with the Gamma-Ray Infrastructure for Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility at TRIUMF. The high efficiency of the GRIFFIN spectrometer allowed 63 $gamma$-ray transitions, with intensities down to $approx$1 part per million (ppm) per $^{62}$Ga $beta^{+}$ decay, to be placed in the level scheme of the daughter nucleus $^{62}$Zn, establishing the superallowed $beta$ branching ratio for $^{62}$Ga decay to be 99.8577$^{+0.0023}_{-0.0029}%$, a factor of 4 more precise than the previous world average. For several cascades, $gamma-gamma$ angular correlation measurements were performed to assign spins and/or determine the mixing ratios of transitions. In particular, the spin of the 2.342 MeV excited state in the daughter nucleus $^{62}$Zn was definitively assigned as $J = 0$. This assignment resolves a discrepancy between previous measurements and has important implications for the isospin symmetry breaking correction, $delta_{C1}$, in $^{62}$Ga superallowed Fermi $beta$ decay.","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77731086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-11-03DOI: 10.1103/PhysRevC.102.054331
A. Kanellakopoulos, Xiaofei Yang, M. Bissell, M. Reitsma, S. Bai, J. Billowes, K. Blaum, A. Borschevsky, B. Cheal, C. Devlin, R. Ruiz, H. Heylen, S. Kaufmann, K. König, Á. Koszorús, S. Lechner, S. Malbrunot-Ettenauer, R. Neugart, G. Neyens, W. Nörtershäuser, T. Ratajczyk, L. V. Rodr'iguez, S. Sels, Shuang Wang, L. Xie, Zhengyu Xu, D. Yordanov
Collinear laser spectroscopy measurements were performed on $^{69,71,73}$Ge isotopes ($Z = 32$) at ISOLDE-CERN. The hyperfine structure of the $4s^2 4p^2 , ^3P_1 rightarrow 4s^2 4p 5s , ^3P_1^o$ transition of the germanium atom was probed with laser light of 269 nm, produced by combining the frequency-mixing and frequency-doubling techniques. The hyperfine fields for both atomic levels were calculated using state-of-the-art atomic relativistic Fock-space coupled-cluster calculations. A new $^{73}$Ge quadrupole moment was determined from these calculations and previously measured precision hyperfine parameters, yielding $Q_{rm s}$ = $-$0.198(4) b, in excellent agreement with the literature value from molecular calculations. The moments of $^{69}$Ge have been revised: $mu$ = +0.920(5) $mu_{N}$ and $Q_{rm s}$= +0.114(8) b, and those of $^{71}$Ge have been confirmed. The experimental moments around $N = 40$ are interpreted with large-scale shell-model calculations using the JUN45 interaction, revealing rather mixed wave function configurations, although their $g$-factors are lying close to the effective single-particle values. Through a comparison with neighboring isotones, the structural change from the single-particle nature of nickel to deformation in germanium is further investigated around $N = 40$.
{"title":"Nuclear moments of germanium isotopes near \u0000N=40","authors":"A. Kanellakopoulos, Xiaofei Yang, M. Bissell, M. Reitsma, S. Bai, J. Billowes, K. Blaum, A. Borschevsky, B. Cheal, C. Devlin, R. Ruiz, H. Heylen, S. Kaufmann, K. König, Á. Koszorús, S. Lechner, S. Malbrunot-Ettenauer, R. Neugart, G. Neyens, W. Nörtershäuser, T. Ratajczyk, L. V. Rodr'iguez, S. Sels, Shuang Wang, L. Xie, Zhengyu Xu, D. Yordanov","doi":"10.1103/PhysRevC.102.054331","DOIUrl":"https://doi.org/10.1103/PhysRevC.102.054331","url":null,"abstract":"Collinear laser spectroscopy measurements were performed on $^{69,71,73}$Ge isotopes ($Z = 32$) at ISOLDE-CERN. The hyperfine structure of the $4s^2 4p^2 , ^3P_1 rightarrow 4s^2 4p 5s , ^3P_1^o$ transition of the germanium atom was probed with laser light of 269 nm, produced by combining the frequency-mixing and frequency-doubling techniques. The hyperfine fields for both atomic levels were calculated using state-of-the-art atomic relativistic Fock-space coupled-cluster calculations. A new $^{73}$Ge quadrupole moment was determined from these calculations and previously measured precision hyperfine parameters, yielding $Q_{rm s}$ = $-$0.198(4) b, in excellent agreement with the literature value from molecular calculations. The moments of $^{69}$Ge have been revised: $mu$ = +0.920(5) $mu_{N}$ and $Q_{rm s}$= +0.114(8) b, and those of $^{71}$Ge have been confirmed. The experimental moments around $N = 40$ are interpreted with large-scale shell-model calculations using the JUN45 interaction, revealing rather mixed wave function configurations, although their $g$-factors are lying close to the effective single-particle values. Through a comparison with neighboring isotones, the structural change from the single-particle nature of nickel to deformation in germanium is further investigated around $N = 40$.","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83888517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-13DOI: 10.1103/physrevc.102.054318
N. Kitamura, K. Wimmer, N. Shimizu, V. Bader, C. Bancroft, D. Barofsky, T. Baugher, D. Bazin, J. Berryman, V. Bildstein, A. Gade, N. I. T. K. C. L. J. L. E. Lunderberg, G. P. F. R. T. Redpath, S. Saenz, D. Smalley, Steven Ragnar Stroberg, J. Tostevin, N. Tsunoda, Y. Utsuno, D. Weisshaar, A. Westerberg
Background: In the "island of inversion", ground states of neutron-rich $sd$-shell nuclei exhibit strong admixtures of intruder configurations from the $fp$ shell. The nucleus $^{30}$Mg, located at the boundary of the island of inversion, serves as a cornerstone to track the structural evolution as one approaches this region. Purpose: Spin-parity assignments for excited states in $^{30}$Mg, especially negative-parity levels, have yet to be established. In the present work, the nuclear structure of $^{30}$Mg was investigated by in-beam $gamma$-ray spectroscopy mainly focusing on firm spin-parity determinations. Method: High-intensity rare-isotope beams of $^{31}$Mg, $^{32}$Mg, $^{34}$Si, and $^{35}$P bombarded a Be target to induce nucleon removal reactions populating states in $^{30}$Mg. $gamma$ rays were detected by the state-of-the-art $gamma$-ray tracking array GRETINA. For the direct one-neutron removal reaction, final-state exclusive cross sections and parallel momentum distributions were deduced. Multi-nucleon removal reactions from different projectiles were exploited to gain complementary information. Results: With the aid of the parallel momentum distributions, an updated level scheme with revised spin-parity assignments was constructed. Spectroscopic factors associated with each state were also deduced. Conclusions: Results were confronted with large-scale shell-model calculations using two different effective interactions, showing excellent agreement with the present level scheme. However, a marked difference in the spectroscopic factors indicates that the full delineation of the transition into the island of inversion remains a challenge for theoretical models.
{"title":"Structure of \u0000Mg30\u0000 explored via in-beam \u0000γ\u0000-ray spectroscopy","authors":"N. Kitamura, K. Wimmer, N. Shimizu, V. Bader, C. Bancroft, D. Barofsky, T. Baugher, D. Bazin, J. Berryman, V. Bildstein, A. Gade, N. I. T. K. C. L. J. L. E. Lunderberg, G. P. F. R. T. Redpath, S. Saenz, D. Smalley, Steven Ragnar Stroberg, J. Tostevin, N. Tsunoda, Y. Utsuno, D. Weisshaar, A. Westerberg","doi":"10.1103/physrevc.102.054318","DOIUrl":"https://doi.org/10.1103/physrevc.102.054318","url":null,"abstract":"Background: In the \"island of inversion\", ground states of neutron-rich $sd$-shell nuclei exhibit strong admixtures of intruder configurations from the $fp$ shell. The nucleus $^{30}$Mg, located at the boundary of the island of inversion, serves as a cornerstone to track the structural evolution as one approaches this region. Purpose: Spin-parity assignments for excited states in $^{30}$Mg, especially negative-parity levels, have yet to be established. In the present work, the nuclear structure of $^{30}$Mg was investigated by in-beam $gamma$-ray spectroscopy mainly focusing on firm spin-parity determinations. Method: High-intensity rare-isotope beams of $^{31}$Mg, $^{32}$Mg, $^{34}$Si, and $^{35}$P bombarded a Be target to induce nucleon removal reactions populating states in $^{30}$Mg. $gamma$ rays were detected by the state-of-the-art $gamma$-ray tracking array GRETINA. For the direct one-neutron removal reaction, final-state exclusive cross sections and parallel momentum distributions were deduced. Multi-nucleon removal reactions from different projectiles were exploited to gain complementary information. Results: With the aid of the parallel momentum distributions, an updated level scheme with revised spin-parity assignments was constructed. Spectroscopic factors associated with each state were also deduced. Conclusions: Results were confronted with large-scale shell-model calculations using two different effective interactions, showing excellent agreement with the present level scheme. However, a marked difference in the spectroscopic factors indicates that the full delineation of the transition into the island of inversion remains a challenge for theoretical models.","PeriodicalId":8464,"journal":{"name":"arXiv: Nuclear Experiment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82633233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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