Nuclear Structure Effects in (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi /><mml:mn>2</mml:mn></mml:math>nucleon) Reactions on the Separated Isotopes of Tellurium at 300 MeV

Schall, Roy F.; Caretto, A.A.

doi:10.1103/physrevc.2.1924

Cited by 7 publications

(3 citation statements)

References 22 publications

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“…The first is a decreasing cross section as S n decreases, i.e. moving towards the neutron dripline, consistent with what was observed for example in [14,34]. The second is an odd-even effect wherein even-Z (proton number) projectiles have a cross section consistently higher than the odd-Z projectiles for the same S n of the daughter nucleus.…”

supporting

confidence: 83%

Prominence of Pairing in Inclusive (p,2p) and (p,pn
Paul¹,
Obertelli²,
Bertulani³
et al. 2019
Phys. Rev. Lett.
7
0
3
0
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Fifty-five inclusive single nucleon removal cross sections from medium mass neutron-rich nuclei impinging on a hydrogen target at ∼ 250 MeV/nucleon were measured at the RIKEN Radioactive Isotope Beam Factory. Systematically higher cross sections are found for proton removal from nuclei with an even number of protons compared to odd-proton number projectiles for a given neutron separation energy. Neutron removal cross sections display no even-odd splitting contrary to nuclear cascade model predictions. Both effects are understood through simple considerations of neutron separation energies and bound state level densities originating in pairing correlations in the daughter nuclei. These conclusions are supported by comparison with semi-microscopic model predictions, highlighting the enhanced role of low-lying level densities in nucleon removal cross sections from loosely-bound nuclei. Pairing correlations, which lower the energy of an atomic nucleus by coupling nucleons into spin-zero pairs, play a prominent role in nuclear structure [1, 2]. They are responsible, for example, for the odd-even mass and nucleon separation energy staggering along isotopic chains and the reduced level density in the low-energy spectra

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supporting

confidence: 83%

Prominence of Pairing in Inclusive (p,2p) and (p,pn
Paul¹,
Obertelli²,
Bertulani³
et al. 2019
Phys. Rev. Lett.
7
0
3
0
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“…The concept of a neutron skin thickness has been presented as a suitable explanation by Caretto and co-workers (38,39) for (p,pn) and (p,2p) cross section trends across a row of cadmium and tellurium iso topes. The "thin" neutron skin hypothesis has been discussed by Karol and Miller(40) in relation to the anomalously low T<i(p,pn) Ni cross section (30 mb at 0.4 GeV compared to a "normal" value of 60 mb).…”

Section: 12c Meutrori Skin Thicknessmentioning

confidence: 99%

Effect of free-particle collisions in high energy proton and pion-induced nuclear reactions

Jacob

1975

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The effect of free-particle collisions in simple "knockout" reactions of the form (a,aN) and in more complex nuclear reactions of the form (a,X) was investigated in a two part study by using protons and pions as the In the second part of this thesis, cross section measurements for (iT.rcN) and other more complex pion-induced spallation reactions were -ixmeasured for the light target nuclei N, 0, and F from 45 to 550 incident pion energy. These measurements indicate rlearly a broad peak in the excitation functions for both (TT.TTN) and fn.X) reactions near 180MeV incident pion energy. This corresponds to the large resonances ob served in the free-particle IT p and ir~p cross sections at the same en ergy. Striking differences in (n,nN) cross section magnitudes are observed among the light nuclei targets. The experimental cross section ratio R _/ + = a(Tr",Tf"n)/a(T7*,TiN) at 180 MeV is 1.7 ± 0.2 for all three targets.The experimental results are compared to previous pion and analogous pro The second stage of this process is the subsequent de-excitation of the excited residual cascade nucleus in a manner similar to that for lew energy nuclear reactions i.e., by emission of nucleons, alpha particles, photons, or even fission fragments. This is termed the "evaporation"stage and has a time scale that is on the order of 10 to 1000 times as long as the cascade stage. Thus, the average de-excitation time for an -20 -18 excited nucleus wouli last about 10 -10 seconds.In light of this mechanism, the wide distribution of product, nu clides formed in a high energy nuclear reaction can be logically explained.Depending upon the complexity of the nucleonic cascade, high as well as low energy deposition events will occur,which in turn, create a wide range of final nuclides after completion of the second or "evaporation" stage of the reaction.-3-This model was further developed by Chew and co-workers (6 Z'j, who proposed the "impulse approximation". This particular approach postulated that the target nucleus would appear to a high energy projectile as a collection of "free" nucleons, rather than an integral cluster, and that the following assumptions should hold (1) The incident particle never in teracts with more than one nucleon at any one time.[2) The amplitude of each incident wave falling on each nucleon is the sane as if the nucleon were a free particle. (3) The binding forces between constituent nucleons in the nucleus are negligible during the strong interaction of the in cident particle with the system.Assumptions (1) and (2) are somewhat oversimplified for systems heavier than the alpha particle. The seemingly paradoxical "impulse"assumption (3) is reconciled by the fact that for very short collision times x, the energy E of the system cannot be determined to better than AE~h/x , a simple application of the uncertainty principle. In spite of these apparent shortcomings, the impulse approximation has been success fully used to correlate a broad spectrum of empirical data and still re mains the basic assumption i...

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“…While these values are significantly lower than have been estimated, 1 they are still within the range expected on the basis of other (/>, 2p) cross sections. 14 The modification of cross sections may help clear up a long-standing discrepancy between fragmentation cross sections for 10 Be production from 16 0 targets as measured by mass spectrometry, 12 compared with those inferred by radiochemical measurements. 15 As we have pointed out elsewhere, 16 cosmic-ray workers have generally adopted the directly measured mass-spectrometer values 1 while those doing meteorite 17 and lunar sample 18 studies have proferred the larger radiochemical values.…”

mentioning

confidence: 99%

Half-Life ofBe10

Yiou

Raisbeck

1972

Phys. Rev. Lett.

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analysis of (6b) shows that for a 4-0, a continuous displacive transition will occur at some X c (a) with X c (a) an increasing function of a. An interesting feature of this instability-driven transition is that the transition becomes increasingly sharp as a -0. Thus, if this were used to model a real physical system, a case could occur in which it would be impossible experimentally to determine that the transition was not first order. The results for (6b) are as shown in Table I. In conclusion, a clearer picture of the transition found in Ref. 4 is now available. In the absence of a symmetry-breaking term there should be no transition. In the presence of one (which could be implicitly introduced through the MFA), there should be a second-order transition. These results are for an idealized model. In a real, physical system, there should be at least a weak symmetry-breaking term. Then, since the transition is of the instability-driven type (with the instability of the Coulomb lattice providing an effective "hump" for the TO mode) there would be a sharp second-order transition with almost a first-order character. If this were accompanied by, for example, a lattice distortion, the transition could be a real, first-order transition.Cosmogenic radionuclides having very long half-lives can be useful dating tools in a number of astrophysical, geophysical, and cosmochemical problems. One of the most prominent of such species is the nuclide 10 Be, which has significant applications in studying the history of cosmic rays, 1 meteorites, 2 lunar samples, 3 marine sediments, 4 and polar deposits. 5 The generally accepted 6 half-life of 10 Be is (2.7 ±0.4)xi0 6 yr, a value based on two separate experiments carried out more than 20 years ago. 7, 8 We have become interested in the question of the accuracy of this number because of its importance in trying to "date" cosmic-ray ages. 1 Although we had no reason to suspect a large error Thus, the first-order character of either the MFA or SPA treatment of the instability-driven transition should not be considered spurious, but rather a strong indication of the inherent instability of the system.We are especially appreciative of a critical examination of our results by W. J. Camp.Any quartic Hamiltonian with a single degree of freedom can be scaled to the form (6). This is also the region where k B T is of the order of the depth of one of the minima of the effective doublewell potential associated with the long-wave length optic mode.in the accepted value, we felt its widespread use warranted an attempt to reduce the error limits. While we have not yet succeeded in that goal, we have found a value which is in strong disagreement with the older number, and which should have important implications in a number of fields of study.The two essential quantities in the determination of any half-life which is too long to be followed directly are the decay rate and the number of atoms of the decaying species, Usually the former can be measured directly, while the latter is obtained by a ma...

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Nuclear Structure Effects in (p,2nucleon) Reactions on the Separated Isotopes of Tellurium at 300 MeV

Cited by 7 publications

References 22 publications

Prominence of Pairing in Inclusive (p,2p) and (p,pn
Paul¹,
Obertelli²,
Bertulani³
et al. 2019
Phys. Rev. Lett.
7
0
3
0
View full text Add to dashboard Cite

Prominence of Pairing in Inclusive (p,2p) and (p,pn
Paul¹,
Obertelli²,
Bertulani³
et al. 2019
Phys. Rev. Lett.
7
0
3
0
View full text Add to dashboard Cite

Effect of free-particle collisions in high energy proton and pion-induced nuclear reactions

Half-Life ofBe10

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Nuclear Structure Effects in (p,2nucleon) Reactions on the Separated Isotopes of Tellurium at 300 MeV

Cited by 7 publications

References 22 publications

Prominence of Pairing in Inclusive (p,2p) and (p,pnPaul1, Obertelli2, Bertulani3 et al. 2019Phys. Rev. Lett.7030View full textAdd to dashboardCite

Prominence of Pairing in Inclusive (p,2p) and (p,pnPaul1, Obertelli2, Bertulani3 et al. 2019Phys. Rev. Lett.7030View full textAdd to dashboardCite

Effect of free-particle collisions in high energy proton and pion-induced nuclear reactions

Half-Life ofBe10

Contact Info

Product

Resources

About

Prominence of Pairing in Inclusive (p,2p) and (p,pn
Paul¹,
Obertelli²,
Bertulani³
et al. 2019
Phys. Rev. Lett.
7
0
3
0
View full text Add to dashboard Cite

Prominence of Pairing in Inclusive (p,2p) and (p,pn
Paul¹,
Obertelli²,
Bertulani³
et al. 2019
Phys. Rev. Lett.
7
0
3
0
View full text Add to dashboard Cite