Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi mathvariant="normal">Am</mml:mi><mml:mprescripts /><mml:none /><mml:mrow><mml:mn>240</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo>(</mml:mo><mml:mi>n</mml:mi><mml:mo>,</mml:mo><mml:mi>f</mml:mi></mml:math>) cross section using the surrogate-ratio method

Casperson, R. J.; Burke, J. T.; Scielzo, N. D.; Escher, Jutta; McCleskey, E.; McCleskey, M.; Saastamoinen, A.; Spiridon, A.; Ratkiewicz, A.; Blanc, A.; Kurokawa, M.; Pizzone, R. G.

doi:10.1103/physrevc.90.034601

Cited by 20 publications

(18 citation statements)

References 29 publications

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“…The experiment was performed at the Cyclotron Institute of Texas A&M University, where two samarium targets, 152 Sm and 154 Sm, approximately 1 mg/cm 2 thick and 98(1)% isotopically enriched were bombarded by a 1.2 nA of 25 MeV proton beam from the K-150 cyclotron. The reaction products were detected by the STARLiTeR setup [19,20] that consisted of a highly segmented ∆E-E charged particle telescope and an array of six HPGe clover detectors with BGO Compton suppression for γ-ray detection.…”

Section: Methodsmentioning

confidence: 99%

First observation of low-energyγ-ray enhancement in the rare-earth region

et al. 2016

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The γ-ray strength function and level density in the quasi-continuum of 151,153 Sm have been measured using BGO shielded Ge clover detectors of the STARLiTeR system. The Compton shields allow for an extraction of the γ strength down to unprecedentedly low γ energies of ≈ 500 keV. For the first time an enhanced lowenergy γ-ray strength has been observed in the rare-earth region. In addition, for the first time both the upbend and the well known scissors resonance have been observed simultaneously for the same nucleus. HauserFeshbach calculations show that this strength enhancement at low γ energies could have an impact of 2-3 orders of magnitude on the (n,γ) reaction rates for the r-process nucleosynthesis.

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Section: Methodsmentioning

confidence: 99%

First observation of low-energyγ-ray enhancement in the rare-earth region

et al. 2016

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“…Further details on the detector arrays, data-taking system, and data analysis can be found in [12,25,29].…”

Section: Methodsmentioning

confidence: 99%

“…While the applicability of the surrogate reaction approach has been successfully demonstrated for (n, f ) cross sections (e.g. * ota2@llnl.gov [8][9][10][11][12][13]), it has been difficult to determine (n, γ) cross sections (e.g., [14][15][16]). …”

Section: Introductionmentioning

confidence: 99%

Spin differences in the Zr90 compound nucleus induced by (p,p′) ,
Ota
¹
,
Burke
²
,
Casperson
³

et al. 2015
Phys. Rev. C
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The effect of the production mechanism on the decay of a compound nucleus is investigated. The nucleus 90 Zr was produced by three different reactions, namely 90 Zr(p, p ) 90 Zr, 91 Zr(p, d) 90 Zr, and 92 Zr(p, t) 90 Zr, which served as surrogate reactions for 89 Zr(n, γ). The spin-parity (J π ) distributions of the states populated by these reactions were studied to investigate the surrogate reaction approach, which aims at indirectly determining cross sections for compound-nuclear reactions involving unstable targets such as 89 Zr. Discrete γ-rays, associated with transitions in 90 Zr and 89 Zr, were measured in coincidence with light ions for scattering angles of 25-60 • and 90 Zr excitation energies extending above the neutron separation energy. The measured transition systematics were used to gain insights into the J π distributions of 90 Zr. The 90 Zr(p, p ) reaction was found to produce fewer γ-rays associated with transitions involving high spin states (J = 6-8 ) than the other two reactions, suggesting that inelastic scattering preferentially populates states in 90 Zr that have lower spins than those populated in the transfer reactions investigated. The γ-ray production was also observed to vary by factors of 2-3 with the angle at which the outgoing particle was detected. These findings are relevant to the application of the surrogate reaction approach.

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“…Some recent applications of this method in the reactions with 3,4 He beams include: 235,238 234,235,236,238 U, 239 Pu(α,α') [345,346,347]. Also (p,p ′ ), (p,d), (p,t) reactions with 239 Pu, 235,238 U, 243 Am targets [169,170] were investigated. In addition, lithium beams were bombarded to 232 Th and 238 U samples to populate CNs in the ( 6 Li,d), ( 6 Li,α), ( 7 Li,t), ( 7 Li,α) reactions [348,168,349,350,351].…”

Section: Fission Probabilities Via the Surrogate Methodmentioning

confidence: 99%

Nuclear fission: a review of experimental advances and phenomenology

2017

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In the last two decades, through technological, experimental and theoretical advances, the situation in experimental fission studies has changed dramatically. With the use of advanced production and detection techniques both much more detailed and precise information can now be obtained for the traditional regions of fission research and, crucially, new regions of nuclei have become routinely accessible for fission studies. This work first of all reviews the recent developments in experimental fission techniques, in particular the resurgence of transfer-induced fission reactions with light and heavy ions, the emerging use of inverse-kinematic approaches, both at Coulomb and relativistic energies, and of fission studies with radioactive beams. The emphasis on the fission-fragment mass and charge distributions will be made in this work, though some of the other fission observables, such as prompt neutron and γ-ray emission will also be reviewed. A particular attention will be given to the low-energy fission in the so far scarcely explored nuclei in the very neutron-deficient lead region. They recently became the focus for several complementary experimental studies, such as β-delayed fission with radioactive beams at ISOLDE(CERN), Coulex-induced fission of relativistic secondary beams at FRS(GSI), and several prompt fusion-fission studies. The synergy of these approaches allows a unique insight in the new region of asymmetric fission around [Formula: see text]Hg, recently discovered at ISOLDE. Recent extensive theoretical efforts in this region will also be outlined. The unprecedented high-quality data for fission fragments, completely identified in Z and A, by means of reactions in inverse kinematics at FRS(GSI) and VAMOS(GANIL) will be also reviewed. These experiments explored an extended range of mercury-to-californium elements, spanning from the neutron-deficient to neutron-rich nuclides, and covering both asymmetric, symmetric and transitional fission regions. Some aspects of heavy-ion induced fusion-fission and quasifission reactions will be also discussed, which reveal their dynamical features, such as the fission time scale. The crucial role of the multi-chance fission, probed by means of multinucleon-transfer induced fission reactions, will be highlighted. The review will conclude with the discussion of the new experimental fission facilities which are presently being brought into operation, along with promising 'next-generation' fission approaches, which might become available within the next decade.

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Measurement of theAm240(n,f) cross section using the surrogate-ratio method

Cited by 20 publications

References 29 publications

First observation of low-energyγ-ray enhancement in the rare-earth region

First observation of low-energyγ-ray enhancement in the rare-earth region

Spin differences in the Zr90 compound nucleus induced by (p,p′) ,
Ota
¹
,
Burke
²
,
Casperson
³

et al. 2015
Phys. Rev. C
Self Cite
23
3
28
0
View full text Add to dashboard Cite

Nuclear fission: a review of experimental advances and phenomenology

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Measurement of theAm240(n,f) cross section using the surrogate-ratio method

Cited by 20 publications

References 29 publications

First observation of low-energyγ-ray enhancement in the rare-earth region

First observation of low-energyγ-ray enhancement in the rare-earth region

Spin differences in the Zr90 compound nucleus induced by (p,p′) , Ota1, Burke2, Casperson3 et al. 2015Phys. Rev. CSelf Cite233280View full textAdd to dashboardCite

Nuclear fission: a review of experimental advances and phenomenology

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About

Spin differences in the Zr90 compound nucleus induced by (p,p′) ,
Ota
¹
,
Burke
²
,
Casperson
³

et al. 2015
Phys. Rev. C
Self Cite
23
3
28
0
View full text Add to dashboard Cite