arXiv subjects

Maya Takechi

Publications and source records attributed to Maya Takechi.

13 recordsLinked to original sources

arXiv2022

Neutron-skin values and matter and neutron radii determined from reaction cross sections of proton scattering on $^{12}$C, $^{40,48}$Ca, $^{58}$Ni, $^{208}$Pb

Very lately, the PREX and the CREX collaboration present skin values, $r_{\rm skin}^{208}({\rm newPREX2}) =0.278 \pm 0.078\ {\rm (exp)} \pm 0.012\ {\rm (theor.)}\,{\rm fm}$ and $r_{\rm skin}^{48}=0.121 \pm 0.026\ {\rm (exp)} \pm 0.024\ {\rm (model)}$, respectively. We recently determined a neutron-skin value $r_{\rm skin}^{208}=0.278 \pm 0.035$fm from measured reaction cross sections $\sigma_{\rm R}({\rm exp})$ of p+$^{208}$Pb scattering in a range of incident energies $10 \lsim E_{\rm in} \lsim 100$ MeV where the chiral (Kyushu) $g$-matrix folding model is reliable for $^{12}$C+$^{12}$C scattering. The data $\sigma_{\rm R}({\rm exp})$ are available for proton scattering on $^{58}$Ni, $^{40,48}$Ca, $^{12}$C targets. Our first aim is to test the Kyushu $g$-matrix folding model for p+$^{208}$Pb scattering in $20 \lsim E_{\rm in} \lsim 180$ MeV. Our second aim is to determine skin values $r_{\rm skin}$ and matter and neutron radii, $r_{\rm m}$ and $r_{\rm n}$, for $^{208}$Pb, $^{58}$Ni, $^{40,48}$Ca, $^{12}$C from the $\sigma_{\rm R}({\rm exp})$. Our method is the Kyushu $g$-matrix folding model with the densities scaled from the D1S-GHFB+AMP densities, where D1S-GHFB+AMP stands for Gogny-D1S HFB (GHFB) with the angular momentum projection (AMP). As for proton scattering, we find that our model is reliable in $20 \lsim E_{\rm in} \lsim 180$ MeV. For $^{208}$Pb, the skin value deduced from $\sigma_{\rm R}({\rm exp})$ in $20 \lsim E_{\rm in} \lsim 180$ MeV is $r_{\rm skin}^{208}(\sigma_{\rm R})=0.299 \pm 0.020$ fm. Our results on $r_{\rm skin}$ are compared with the previous works. Our result $r_{\rm skin}^{208}(\sigma_{\rm R}) = 0.299 \pm 0.020$ fm agrees with $r_{\rm skin}^{208}({\rm PREX2}) = 0.283\pm 0.071$ fm. In addition, our result $r_{\rm skin}^{48}=0.103 \pm 0.022$ fm is consistent with the CREX value.

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arXiv2022

Matter radii and skins of $^{6,8}$He from reaction cross section of proton+$^{6,8}$He scattering based on the Love-Franey $t$-matrix model (published in Results in Physics)

For $^{4,6,8}$He, Tanihata et al. determined matter radii $r_{m}(\sigma_{\rm I})=1.57(4), 2.48(3), 2.52(3)$~fm from interaction cross sections $\sigma_{\rm I}$ for $^{4,6,8}$He scattering on Be, C Al targets at 790~MeV/nucleon. Lu et al. measured the atomic isotope shifts (AIS) for $^{4,6,8}$He and determined proton radii $r_{p}({\rm AIS})$ for $^{4,6,8}$He. As for p+$^{4,6,8}$He scattering, reaction cross sections $\sigma_{\rm R}({\rm exp})$ are available at 700~MeV with high accuracy. Our aim is to determine matter radii $r_{m}$ and skins $r_{\rm skin}$ for $^{6,8}$He from the $\sigma_{\rm R}({\rm exp})$ and the $r_{p}({\rm AIS})$. {\bf Method:} Our model is the Love-Franey $t$-matrix folding model, since the model is better than the optical limit of Glauber model. Our results for $^{6,8}$He are $r_{m}({\rm exp})=2.48(3), 2.53(2)$~fm and $r_{\rm skin}=$0.78(3), 0.82(2)~fm. For $^{6,8}$He, our results $r_{m}(\sigma_{\rm R})$ agree with those of Tanihata {\it et al.}. For $^{8}$He, the distance between $^{4}$He and the center of mass of valence four neutrons is 2.367~fm.

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arXiv2022

Neutron skin in $^{48}$Ca determined from p+$^{48}$Ca and $^{48}$Ca+$^{12}$C scattering

In our previous paper, we determined $r_{\rm skin}^{208}({\rm exp})=0.278 \pm 0.035$~fm from $\sigma_{\rm R}$ for p+$^{208}$Pb scattering, using the Kyushu (chiral) $g$-matrix folding model with the densities calculated with D1S-GHFB with the angular momentum projection (AMP). The value agrees with that of PREX2. Reaction cross sections $\sigma_{\rm R}$ are available for p+$^{48}$Ca scattering, whereas interaction cross sections $\sigma_{\rm I}$ are available for $^{48}$Ca + $^{12}$C scattering. As for $^{48}$Ca, the high-resolution $E1$ polarizability experiment ($E1$pE) yields $r_{\rm skin}^{48}(E1{\rm pE}) =0.14 \sim 0.20~{\rm fm}$. We determine $r_{\rm skin}^{48}({\rm exp})$ from the data on $\sigma_{\rm R}$ for p+$^{48}$Ca scattering and from the data on $\sigma_{\rm I}$ for $^{48}$Ca+$^{12}$C scattering. We use the Kyushu $g$-matrix folding model with the densities calculated with the D1M-GHFB+AMP densities. The D1M-GHFB+AMP proton and neutron densities are scaled so as to reproduce the data under the condition that the radius $r_{\rm p}$ of the scaled proton density equals the data $r_{\rm p}({\rm exp})$ determined from the electron scattering. We deduce skin values $r_{\rm skin}=r_{\rm n}({\rm exp})-r_{\rm p}({\rm exp})$ from the resulting $r_{\rm n}({\rm exp})$ and the $r_{\rm p}({\rm exp})$ determined from electron scattering. The same procedure is taken for D1S-GHFB+AMP. We regard $r_{\rm skin}^{48}(E1{\rm pE})$ as a reference skin value. Using the reference skin value and taking D1M-GHFB+AMP, we determine $r_{\rm skin}^{48}({\rm exp})=0.158 \pm 0.025$~fm for p+$^{48}$Ca scattering and $0.160 \pm 0.058$~fm for $^{48}$Ca + $^{12}$C scattering. We take the weighted mean and its error for the two skin values. The result is $r_{\rm skin}^{48}({\rm exp})=0.158 \pm (0.023)_{\rm exp} \pm (0.012)_{\rm th}~{\rm fm}$.

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arXiv2021

Reaction cross section of proton scattering consistent with PREX-II (published in Results in Physics)

Background: The neutron skin thickness $R_{\rm skin}^{\rm PV}$ of PREX-II is presented in Phys. Rev. Lett. {\bf 126}, 172502 (2021). The reaction cross section $\sigma_R$ is useful to determine the matter radius $R_m$ and $R_{\rm skin}$. For proton scattering, the reaction cross section $\sigma_R$ are available for $E_{\rm in} > 400$ MeV. Method and results: We determine $R_n^{\rm exp}=5.727 \pm 0.071$ fm and $R_m^{\rm exp}=5.617 \pm 0.044$ fm from $R_p^{\rm exp}$ = 5.444 fm and $R_{\rm skin}^{\rm PV}$. The $R_p^{\rm GHFB}$ calculated with D1S-GHFB with the angular momentum projection (AMP). agrees with $R_p^{\rm exp}$. The neutron density calculated with GHFB+AMP is scaled so as to $R_n^{\rm scaling}=5.727$ fm. The Love-Franey $t$-matrix model with the scaled densities reproduces the data on $\sigma_R$. Aim: Our aim is to find the $\sigma_R$ of proton scattering consistent with $R_{\rm skin}^{\rm PV}$. Conclusion: The $\sigma_R$ of proton scattering consistent with $R_{\rm skin}^{\rm PV}$ are $\sigma_R^{\rm exp}$ at $E_{\rm in} = 534.1, 549, 806$ MeV.

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arXiv2020

Determination of matter radius and neutron skin of $^{58}$Ni from reaction cross section of proton+$^{58}$Ni scattering based on chiral $g$-matrix model

Background: Using the chiral (Kyushu) $g$-matrix folding model with the densities calculated with Gogny-HFB (GHFB) with the angular momentum projection (AMP), we determined the central values of matter radius and neutron skin from the central values of reaction cross sections $\sigma_{\rm R}({\rm EXP})$ of p+$^{40,48}$Ca and p+$^{208}$Pb scattering. As for p+$^{58}$Ni scattering, $\sigma_{\rm R}({\rm EXP})$ are available as a function of incident energy $E_{\rm in}$. Aim: Our aim is to determine matter radius $r_{m}$ and skin $r_{\rm skin}$ for $^{58}$Ni from the $\sigma_{\rm R}({\rm EXP})$ of p+$^{58}$Ni scattering by using the Kyushu $g$-matrix folding model with the GHFB+AMP densities. Results: For p+$^{58}$Ni scattering, the Kyushu $g$-matrix folding model with the GHFB+AMP densities reproduces $\sigma_{\rm R}({\rm EXP})$ in $8.8 \leq E_{\rm in} \leq 81$MeV. For $E_{\rm in}=81$MeV, we define the factor $F$ as $F=\sigma_{\rm R}({\rm EXP})/\sigma_{\rm R}({\rm AMP})=0.9775$. The $F\sigma_{\rm R}({\rm AMP})$ be much the same as the center values of $\sigma_{\rm R}({\rm EXP})$ in $8.8 \leq E_{\rm in} \leq 81$MeV. We then determine $r_{\rm m}({\rm EXP})$ from the center values of $\sigma_{\rm R}({\rm EXP})$, using $\sigma_{\rm R}({\rm EXP})=C r_{m}^{2}({\rm EXP})$ with $C=r_{m}^{2}({\rm AMP})/ (F\sigma_{\rm R}({\rm AMP}))$. The $r_{m}({\rm EXP})$ thus obtained are averaged over $E_{\rm in}$. The averaged value is $r_{m}({\rm EXP})=3.697$fm. Eventually, we obtain $r_{\rm skin}({\rm EXP})=0.023$fm from $r_{\rm m}=3.697$fm and $r_p({\rm EXP})=3.685$fm of electron scattering.

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arXiv2020

Folding-model approach to reaction cross section of $^{4,6,8}$He+$^{12}$C scattering at 790 MeV (published in Results in Physics)

Tanihata {\it et al.} determined matter radii $r_{m}(\sigma_{\rm I})$ for $^{4,6,8}$He from interaction cross sections $\sigma_{\rm I}$ of $^{4,6,8}$He+$^{12}$C scattering at 790 MeV per nucleon, using the optical limit of the Glauber model. Lu {\it et al.} determined proton radii $r_{p}({\rm AIS})$ for $^{4,6,8}$He with the atomic isotope shifts (AIS). We investigate whether the Love-Franey $t$-matrix folding model is good for $^{4,6,8}$He+$^{12}$C scattering at 790 MeV per nucleon.

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arXiv2020

Neutron skin $r_{\rm skin}^{48}$ determined from reaction cross section of proton+$^{48}$Ca scattering

{\bf Background:} Using the chiral (Kyushu) $g$-matrix folding model with the densities calculated with GHFB+AMP, we determined $r_{\rm skin}^{208}=0.25$fm from the central values of $\sigma_{\rm R}$ of p+$^{208}$Pb scattering in $E_{\rm in}=40-81$MeV. The high-resolution $E1$ polarizability experiment ($E1$pE) yields $r_{\rm skin}^{48}(E1{\rm pE}) =0.14-0.20$fm. The data on $\sigma_{\rm R}$ are available as a function of $E_{\rm in}$ for $p$+$^{48}$Ca scattering. {\bf Aim:} Our aim is to determine $r_{\rm skin}^{48}$ from the central values of $\sigma_{\rm R}$ for $p$+$^{48}$Ca scattering by using the folding model. {\bf Results:} As for $^{48}$Ca, we determine $r_n(E1{\rm pE})=3.56$fm from the central value 0.17fm of $r_{\rm skin}^{48}(E1{\rm pE})$ and $r_p({\rm EXP})=3.385$fm of electron scattering, and evaluate $r_m(E1{\rm pE})=3.485$fm from the $r_n(E1{\rm pE})$ and the $r_p({\rm EXP})$ of electron scattering. The folding model with GHFB+AMP densities reproduces $\sigma_{\rm R}$ in $23 \leq E_{\rm in} \leq 25.3$ MeV in one-$\sigma$ level, but slightly overestimates the central values of $\sigma_{\rm R}$ there. In $23 \leq E_{\rm in} \leq 25.3$MeV, the small deviation allows us to scale the GHFB+AMP densities to the central values of $r_p({\rm EXP})$ and $r_n(E1{\rm pE})$. The $\sigma_{\rm R}(E1{\rm pE})$ obtained with the scaled densities almost reproduce the central values of $\sigma_{\rm R}$ when $E_{\rm in}=23-25.3$MeV, so that the $\sigma_{\rm R}({\rm GHFB+AMP})$ and the $\sigma_{\rm R}(E1{\rm pE})$ are in 1-$\sigma$ of $\sigma_{\rm R}$ there. In $E_{\rm in}=23-25.3$MeV, we determine the $r_{m}({\rm EXP})$ from the central values of $\sigma_{\rm R}$ and take the average for the $r_{m}({\rm EXP})$. The averaged value is $r_{m}({\rm EXP})=3.471$fm. Eventually, we obtain $r_{\rm skin}^{48}({\rm EXP})=0.146$fm from $r_{m}({\rm EXP})=3.471$fm and $r_p({\rm EXP})=3.385$fm.

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arXiv2020

Neutron skin thickness of ${}^{208}$Pb determined from reaction cross section for proton scattering

The reaction cross section $\sigma_R$ is useful to determine the neutron radius $R_n$ as well as the matter radius $R_m$. The chiral (Kyushu) $g$-matrix folding model for $^{12}$C scattering on $^{9}$Be, $^{12}$C, $^{27}$Al targets was tested in the incident energy range of $30 \lsim E_{\rm in} \lsim 400 $ MeV, and it is found that the model reliably reproduces the $\sigma_R$ in $30 \lsim E_{\rm in} \lsim 100 $ MeV and $250 \lsim E_{\rm in} \lsim 400$ MeV. \item[Aim] We determine $R_n$ and the neutron skin thickness $R_{\rm skin}$ of ${}^{208}{\rm Pb}$ by using high-quality $\sigma_R$ data for the $p+{}^{208}{\rm Pb}$ scattering in $30 \leq E_{\rm in} \leq 100$ MeV. The theoretical model is the Kyushu $g$-matrix folding model with the densities calculated with Gongny-D1S HFB (GHFB) with the angular momentum projection (AMP). \item[Results] The Kyushu $g$-matrix folding model with the GHFB+AMP densities underestimates $\sigma_{\rm R}$ in $30 \leq E_{\rm in} \leq 100$~MeV only by a factor of 0.97. Since the proton radius $R_p$ calculated with GHFB+AMP agrees with the precise experimental data of 5.444 fm, the small deviation of the theoretical result from the data on $\sigma_R$ allows us to scale the GHFB+AMP neutron density so as to reproduce the $\sigma_R$ data. In $E_{\rm in}$ = 30--100 MeV, the experimental $\sigma_R$ data can be reproduced by assuming the neutron radius of ${}^{208}{\rm Pb}$ as $R_n$ = $5.722 \pm 0.035$ fm. \item[Conclusion] The present result $R_{\rm skin}$ = $0.278 \pm 0.035$ fm is in good agreement with the recent PREX-II result of $r_{\rm skin}$ = $0.283\pm 0.071$ fm.

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arXiv2020

Reanalyses for $^{42-51}$Ca scattering on a $^{12}$C target at $280$ MeV/nucleon based on chiral $g$ folding mode with Gogny-D1S Hartree-Fock-Bogoliubov densities (published in Results in Physics)

In the previous paper, we predicted reaction cross sections $\sigma_{\rm R}$ for $^{40-60,62,64}$Ca+$^{12}$C scattering at $280$~MeV/nucleon, since Tanaka {\it el al.} measured interaction cross sections $\sigma_{\rm I}$ for $^{42-51}$Ca in RIKEN and determined neutron skin $r_{\rm skin}({\rm RIKEN})$ using the optical limit of the Glauber model with the Woos-Saxon densities. Our purpose is to reanalyze the $r_{\rm skin}$ from the $\sigma_{\rm I}$. Our analysis is superior to theirs, since the chiral $g$-matrix folding model (the GHFB and GHFB+AMP densities) is much better than the optical limit of the Glauber model (the Woos-Saxon densities). Our model is the chiral $g$-matrix folding model with the densities scaled from the GHFB and GHFB+AMP densities. We scale the GHFB and GHFB+AMP densities so that the $\sigma_{\rm R}$ of the scaled densities can agree with the central values of $\sigma_{\rm I}$ under the condition that the proton radius of the scaled proton density equals the data determined from the isotope shift based on the electron scattering. The $r_{\rm skin}$ thus determined are close to their results $r_{\rm skin}^{42-51}({\rm RIKEN})$. For $^{48}$Ca, our value $r_{\rm skin}^{48}$ is 0.105 $\pm$ 0.06~fm, while their value is $r_{\rm m}^{48}({\rm RIKEN})=0.146 \pm 0.06$~fm. We take the weighted mean and its error of $r_{\rm skin}^{48}(\sigma_{\rm I})= 0.105 \pm 0.06$~fm and $r_{\rm skin}^{48}(E1{\rm pE}) =0.17 \pm 0.03$~fm of the high-resolution $E1$ polarizability experiment (E1{\rm pE}). Our final result is $r_{\rm skin}^{48}=0.157 \pm 0.027$~fm. Our conclusion is $r_{\rm skin}^{48}=0.157 \pm 0.027$~fm for $^{48}$Ca. For $^{42-47,49-51}$Ca, our results on $r_{\rm skin}$ are similar to theirs. Our result for $^{48}$Ca is related to CREX.

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arXiv2020

Neutron skin of $^{48}$Ca consistent with experimental data on skins

[Background]: In our previous paper, we predicted $r_{\rm skin}$, $r_{\rm p}$, $r_{\rm n}$, $r_{\rm m}$ for $^{40-60,62,64}$Ca after determining the neutron dripline, using the Gogny-D1S HFB with and without the angular momentum projection (AMP). We found that effects of the AMP are small. Very lately, Tanaka {\it et al.} measured interaction cross sections $\sigma_{\rm I}$ for $^{42-51}$Ca, determined $r_{\rm m}$ from the $\sigma_{\rm I}$, and deduced skin $r_{\rm skin}$ and $r_{\rm n}$ from the $r_{\rm m}$ and the $r_{\rm p}(\rm {exp})$ evaluated from the electron scattering. Comparing our results with the data, we find for $^{42-48}$Ca that GHFB and GHFB+AMP reproduce the data on $r_{\rm skin}$, $r_{\rm n}$, $r_{\rm m}$, but not for $r_{\rm p}(\rm {exp})$. [Aim]: Our purpose is to determine a value of $r_{\rm skin}^{48}$ by using GHFB+AMP and the constrained GHFB (cGHFB) in which the calculated value is fitted to $r_{\rm p}(\rm {exp})$. [Results]: For $^{42,44,46,48}$Ca, cGHFB hardly changes $r_{\rm skin}$, $r_{\rm m}$, $r_{\rm n}$ calculated with GHFB+AMP, except for $r_{\rm skin}^{48}$. For $r_{\rm skin}^{48}$, the cGHFB result is $r_{\rm skin}^{48}=0.190$fm, while $r_{\rm skin}^{48}=0.159$fm for GHFB+AMP. We should take the upper and the lower bound of GHFB+AMP and cGHFB. The result $r_{\rm skin}^{48}=0.159-0.190$fm consists with the $r_{\rm skin}^{48}(\sigma_{\rm I})$ and the data $r_{\rm skin}^{48}(\rm $E1$pE)$ obtained from high-resolution $E1$ polarizability experiment ($E1$pE). Using the $r_{\rm skin}^{48}$-$r_{\rm skin}^{208}$ relation with strong correlation of Ref.[3], we transform the data $r_{\rm skin}^{208}$ determined by PREX and $E1$pE to the corresponding values, $r_{\rm skin}^{48}(\rm tPREX)$ and $r_{\rm skin}^{48}(\rm t$E1$pE)$. Our result is consistent also for $r_{\rm skin}^{48}(\rm tPREX)$ and $r_{\rm skin}^{48}(\rm t$E1$pE)$.

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arXiv2019

$g$-matrix folding-model approach to reaction cross sections for scattering of Ca isotopes on a C target

We first predict the ground-state properties of Ca isotopes, using the Gogny-D1S Hartree-Fock-Bogoliubov (GHFB) with and without the angular momentum projection (AMP). We find that $^{64}$Ca is an even-dripline nucleus and $^{59}$Ca is an odd-dripline nucleus, using $A$ dependence of the one-neutron separation energy $S_{1}$ and the two-neutron separation energy, $S_{2}$. As for $S_{1}$, $S_{2}$ and the binding energies $E_{\rm B}$, our results agree with the experimental data in $^{40-58}$Ca. As other ground-state properties of $^{40-60,62,64}$Ca, we predict charge, proton, neutron, matter radii, neutron skin and deformation. As for charge radii, our results are consistent with the experimental data in $^{40-52}$Ca. For $^{48}$Ca, our results on proton, neutron, matter radii agree with the experimental data. Very lately, Tanaka et. al. measured interaction cross sections for $^{42-51}$Ca scattering on a $^{12}$C target at an incident energy per nucleon of $E_{\rm lab}=280$MeV. Secondly, we predict reaction cross sections $\sigma_{\rm R}$ for $^{40-60,62,64}$Ca, using a chiral $g$-matrix double-folding model (DFM). To show the reliability of the present DFM for $\sigma_{\rm R}$, we apply the DFM for the data on $^{12}$C scattering on $^{9}$Be, $^{12}$C, $^{27}$Al targets in $30 < E_{\rm lab} < 400 $MeV, and show that the present DFM is good in $30 < E_{\rm lab} < 100 $MeV and $250 < E_{\rm lab} < 400 $MeV. For $110 < E_{\rm lab} < 240 $MeV, our results have small errors. To improve the present DFM for $\sigma_{\rm R}$, we propose two prescriptions.

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arXiv2014

Ground-state properties of neutron-rich Mg isotopes

We analyze recently-measured total reaction cross sections for 24-38Mg isotopes incident on 12C targets at 240 MeV/nucleon by using the folding model and antisymmetrized molecular dynamics(AMD). The folding model well reproduces the measured reaction cross sections, when the projectile densities are evaluated by the deformed Woods-Saxon (def-WS) model with AMD deformation. Matter radii of 24-38Mg are then deduced from the measured reaction cross sections by fine-tuning the parameters of the def-WS model. The deduced matter radii are largely enhanced by nuclear deformation. Fully-microscopic AMD calculations with no free parameter well reproduce the deduced matter radii for 24-36Mg, but still considerably underestimate them for 37,38Mg. The large matter radii suggest that 37,38Mg are candidates for deformed halo nucleus. AMD also reproduces other existing measured ground-state properties (spin-parity, total binding energy, and one-neutron separation energy) of Mg isotopes. Neutron-number (N) dependence of deformation parameter is predicted by AMD. Large deformation is seen from 31Mg with N = 19 to a drip-line nucleus 40Mg with N = 28, indicating that both the N = 20 and 28 magicities disappear. N dependence of neutron skin thickness is also predicted by AMD.

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arXiv2010

Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon

A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were analyzed and identified by using the superconducting in-flight separator BigRIPS. We observed 45 new neutron-rich isotopes: 71Mn, 73,74Fe, 76Co, 79Ni, 81,82Cu, 84,85Zn, 87Ga, 90Ge, 95Se, 98Br, 101Kr, 103Rb, 106,107Sr, 108,109Y, 111,112Zr, 114,115Nb, 115,116,117Mo, 119,120Tc, 121,122,123,124Ru, 123,124,125,126Rh, 127,128Pd, 133Cd, 138Sn, 140Sb, 143Te, 145I, 148Xe, and 152Ba.

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