松原 礼明

We have measured the differential cross section and analyzing power for (p, 2p) reactions that lead to discrete states of residual nuclei at an incident energy of 197 MeV for five kinds of target nuclei, 12C, 16O, 40,48Ca, and 90Zr. The data are compared with distorted-wave impulse approximation calculations using two kinds of global optical potentials. The spectroscopic factors obtained from these calculations agree with those determined in (e, e′p) studies within 20%, except for one orbital of the 90Zr nucleus where the distortion effect is much greater than that for the other orbitals of 90Zr and for other target nuclei. We also observed a clear and visibly distinct j-dependence in the analyzing power.

The electric dipole strength distribution in Ca40 between 5 and 25 MeV has been determined at RCNP, Osaka, from proton inelastic scattering experiments at very forward angles. Combined with total photoabsorption data at higher excitation energy, this enables an extraction of the electric dipole polarizability αD(40Ca)=1.92(17) fm3. Together with the measured αD in Ca48, it provides a stringent test of modern theoretical approaches, including coupled-cluster calculations with chiral effective field theory interactions and state-of-the art energy density functionals. The emerging picture is that for this medium-mass region dipole polarizabilities are well described theoretically, with important constraints for the neutron skin in Ca48 and related equation of state quantities.

<title>Abstract</title> Cardiac implantable electronic devices (CIEDs) were believed to have a tolerance dose and that direct irradiation has to be avoided. Thus, no clinical guidelines have mentioned the feasibility of total body irradiation (TBI) with a CIED directly. The purpose of this work was to study a feasible and safe condition for TBI using a CIED. Eighteen CIEDs were directly irradiated by a 6-MV X-ray beam, where a non-neutron producible beam was employed for the removal of any neutron contribution to CIED malfunction. Irradiation up to 10 Gy in accumulated dose was conducted with a 100-cGy/min dose rate, followed by up to 20 Gy at 200 cGy/min. An irradiation test of whether inappropriate ventricular shock therapy was triggered or not was also performed by using a 6-MV beam of 5, 10, 20 and 40 cGy/min to two CIEDs. No malfunction was observed during irradiation up to 20 Gy at 100 and 200 cGy/min without activation of shock therapy. These results were compared with typical TBI, suggesting that a CIED in TBI will not encounter malfunction because the prescribed dose and the dose rate required for TBI are much safer than those used in this experiment. Several inappropriate shock therapies were, however, observed even at 10 cGy/min if activated. The present result suggested that TBI was feasible and safe if a non-neutron producible beam was employed at low dose-rate without activation of shock therapy, where it was not inconsistent with clinical and non-clinical data in the literature. The feasibility of TBI while using a CIED was discussed for the first time.

<title>Abstract</title> We searched for the $\alpha$ condensed state in $^{13}$C by measuring the $\alpha$ inelastic scattering at $E_\alpha = 388$ MeV at forward angles including 0$^\circ$. We performed a distorted-wave Born approximation calculation with the single-folding potential and multipole decomposition analysis to determine the isoscalar transition strengths in $^{13}$C. We found a bump structure around $E_x = 12.5$ MeV due to the isoscalar monopole ($IS0$) transition. A peak-fit analysis suggested that this bump consisted of several $1/2^-$ states. We propose that this bump is due to the mirror state of the 13.5 MeV state in $^{13}$N, which dominantly decays to the $\alpha$ condensed state in $^{12}$C. It was speculated that the $1/2^-$ states around $E_x = 12.5$ MeV were candidates for the $\alpha$ condensed state, but the $3\alpha + n$ orthogonality condition model suggests that the $\alpha$ condensed state is unlikely to emerge as the negative parity states. We also found two $1/2^+$ or $3/2^+$ states at $E_x = 14.5$ and 16.1 MeV excited with the isoscalar dipole ($IS1$) strengths. We suggest that the 16.1 MeV state is a possible candidate for the $\alpha$ condensed state predicted by the cluster model calculations on the basis of the good correspondence between the experimental and calculated level structures. However, the theoretical $IS1$ transition strength for this state is significantly smaller than the measured value. Further experimental information is strongly desired to establish the $\alpha$ condensed state in $^{13}$C.

Spin-<inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:mi>M</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:math></inline-formula> excitations of nuclei are important for describing neutrino reactions in supernovae or in neutrino detectors since they are allowed transitions mediated by neutral current neutrino interactions. The spin-<inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"><mml:mrow><mml:mi>M</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:math></inline-formula> excitation strength distributions in self-conjugate <inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m3"><mml:mrow><mml:mi>N</mml:mi><mml:mo>=</mml:mo><mml:mi>Z</mml:mi></mml:mrow></mml:math></inline-formula> nuclei were studied by proton inelastic scattering at forward angles for each of isovector and isoscalar excitations as reported in H. Matsubara et al., Phys. Rev. Lett. <bold>115</bold>, 102501 (2015). The experiment was carried out at the Research Center for Nuclear Physics, Osaka University, employing a proton beam at 295 MeV and the high-resolution spectrometer Grand Raiden. The measured cross-section of each excited state was converted to the squared nuclear matrix elements of spin-<inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m4"><mml:mrow><mml:mi>M</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:math></inline-formula> transitions by applying a unit cross-section method. Comparison with predictions by a shell-model has revealed that isoscalar spin-<inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m5"><mml:mrow><mml:mi>M</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:math></inline-formula> strengths are not quenched from the prediction although isovector spin-<inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m6"><mml:mrow><mml:mi>M</mml:mi><mml:mn>1</mml:mn></mml:mrow></mml:math></inline-formula> strengths are quenched similarly with Gamow-Teller strengths in charged-current reactions. This finding hints at an important origin of the quenching of the strength relevant to neutrino scattering, that is, the proton-neutron spin-spin correlation in the ground state of the target nucleus. In this manuscript we present the details of the unit cross-section method used in the data analysis and discuss the consistency between the quenching of the isoscalar magnetic moments and that of the isoscalar spin-M1 strengths.

<title>ABSTRACT</title> This publication is an English version of the Japanese Society for Radiation Oncology (JASTRO) and The Japanese Circulation Society official guidelines for patients with cardiac implantable electronic devices (CIEDs). Several radiotherapy-associated malfunctions have been reported for CIEDs such as pacemakers and implantable cardioverter-defibrillators. Accordingly, guidelines for radiotherapy in patients with CIEDs have been issued by other countries and societies. In August 2010, JASTRO published the ‘Radiotherapy Guidelines for Patients with Pacemakers and Implantable Defibrillators’ (hereafter referred to as the former guidelines). Given new findings in this decade, a multidisciplinary working group of radiation oncologists, medical physicists, radiation therapists and cardiologists jointly reviewed and revised the former guidelines.

<title>Abstract</title> We have measured the differential cross-sections and analyzing powers for ($p,2p$) reactions at an incident energy of 392 MeV on $^{12}$C, $^{16}$O, $^{40}$Ca, and $^{208}$Pb nuclei, leading to discrete states of the residual nuclei. The data are compared with two kinds of distorted-wave impulse approximation (DWIA) calculations, a standard calculation using a global optical potential and a calculation using wave functions generated in a relativistic Hartree model. The spectroscopic factors deduced from these two calculations agree with those determined in ($e,e'p$) studies mostly within 15% in the case of the lighter three target nuclei. However, those for the $^{208}$Pb target are overestimated compared with the ($e,e'p$) results. In the heavy target case, the DWIA results are very sensitive to the radius parameter of the bound-state potential and thus a careful treatment is required. Regarding the analyzing powers of the present measurement, we confirmed that the $j$-dependence is sufficient for practical spectroscopic use.

The structure of a neutron-rich F25 nucleus is investigated by a quasifree (p,2p) knockout reaction at 270A MeV in inverse kinematics. The sum of spectroscopic factors of π0d5/2 orbital is found to be 1.0±0.3. However, the spectroscopic factor with residual O24 nucleus being in the ground state is found to be only 0.36±0.13, while those in the excited state is 0.65±0.25. The result shows that the O24 core of F25 nucleus significantly differs from a free O24 nucleus, and the core consists of ∼35% O24g.s.. and ∼65% excited O24. The result may infer that the addition of the 0d5/2 proton considerably changes neutron structure in F25 from that in O24, which could be a possible mechanism responsible for the oxygen dripline anomaly.

PURPOSE: Cardiac implantable electronic devices (CIEDs) were believed to possess a tolerance dose to malfunction during radiotherapy. Although recent studies have qualitatively suggested neutrons as a cause of malfunction, numerical understanding has not been reached. The purpose of this work is to quantitatively clarify the contribution of secondary neutrons from out-of-field irradiation to the malfunction of CIEDs as well as to deduce the frequency of malfunctions until completion of prostate cancer treatment as a typical case. MATERIALS AND METHODS: Measured data were gathered from the literature and were re-analyzed. Firstly, linear relationship for a number of malfunctions to the neutron dose was suggested by theoretical consideration. Secondly, the accumulated number of malfunctions of CIEDs gathered from the literature was compared with the prescribed dose, scattered photon dose, and secondary neutron dose for analysis of their correlation. Thirdly, the number of malfunctions during a course of prostate treatment with high-energy X-ray, passive proton and passive carbon-ion beams was calculated while assuming the same response to malfunctions, where X-rays consisted of 6-MV, 10-MV, 15-MV, and 18-MV beams. Monte Carlo simulation assuming simple geometry was performed for the distribution of neutron dose from X-ray beams, where normalization factors were applied to the distribution so as to reproduce the empirical values. RESULTS: Linearity between risk and neutron dose was clearly found from the measured data, as suggested by theoretical consideration. The predicted number of malfunctions until treatment completion was 0, 0.02±0.01, 0.30±0.08, 0.65±0.17, 0.88±0.50, and 0.14±0.04 when 6-MV, 10-MV, 15-MV, 18-MV, passive proton, and passive carbon-ion beams, respectively, were employed, where the single model response to a malfunction of 8.6±2.1 Sv-1 was applied. CONCLUSIONS: Numerical understanding of the malfunction of CIEDs has been attained for the first time. It has been clarified that neutron dose is a good scale for the risk of CIEDs in radiotherapy. Prediction of the frequency of malfunction as well as discussion of the risk to CIEDs in radiotherapy among the multiple modalities have become possible. Because the present study quantitatively clarifies the neutron contribution to malfunction, revision of clinical guidelines is suggested.

© 2019 American Physical Society. Using the high-resolution O18(He3,t)F18 reaction at 0 and at 140 MeV/nucleon, Gamow-Teller (GT) transitions were studied. A high energy resolution of 31 keV was achieved by applying dispersion matching techniques. The main part of the observed GT transition strength is concentrated in the transition to the F18 ground state (g.s.). The absolute values of the reduced GT transition strengths, B(GT), were derived up to Ex=12 MeV assuming proportionality between the B(GT) values and the reaction cross sections at 0. The B(GT) value obtained from the β decay of F18 (g.s.) →O18 (g.s.) was used to determine the proportionality constant. A total B(GT) of 4.06(5) was found and 76(1)% of the strength is concentrated to the ground state of F18. The obtained B(GT) values were compared with those from the O18(p,n)F18 reaction and the mirror symmetric β+ decay of Ne18→F18. The candidates for 1+ states with isospin T=1 were identified by comparison with the O18(p,p′) data. The results of shell-model and quasiparticle-random-phase approximation calculations suggest constructive contributions of various configurations to the F18 ground state, suggesting that this state is the low-energy super GT state.

© 2018 A high position resolution neutron detector for time-of-flight measurements is being developed to measure the [Formula presented] reaction in inverse kinematics with an excitation energy resolution of 1 MeV at the RIKEN RI Beam Factory. In this study, a new method based on the segmentation of the neutron detector part is employed to achieve a position resolution on the order of mm with a prototype neutron detector. The prototype detector consists of 8 × 8 scintillating fibers, two multi-anode photomultiplier tubes (PMTs) and two light guides. The scintillating fibers have a cross sectional area of [Formula presented]. The prototype's performance is studied using the neutron and proton beams provided at the Cyclotron and Radioisotope Center (CYRIC), Tohoku University and the Research Center for Nuclear Physics (RCNP), Osaka University. It is confirmed that the hit pattern analysis correctly recognizes the neutron detection position within the fiber size of 3.75 mm. The obtained TOF resolution of 350 ps (FWHM), lateral position resolution of 2.5 mm (FWHM), and longitudinal position resolution of 50–60 mm (FWHM) satisfy the requirements to achieve an excitation energy resolution of 1 MeV. The typical detection efficiency is [Formula presented]2.0% for a neutron with a kinetic energy of 50–200 MeV. The detailed investigation of the detection efficiency in conjunction with the neutron hit position reveals the existence of the non-uniformity of the efficiency. It is shown that the non-uniformity can be mitigated by reducing the threshold level, and by increasing the detector size. For a larger neutron detector, based on the design of the prototype detector, the non-uniformity will thus be negligible.

A set of high-resolution zero-degree inelastic proton scattering data on Mg24, Si28, S32, and Ca40 provides new insight into the long-standing puzzle of the origin of fragmentation of the giant dipole resonance (GDR) in sd-shell nuclei. Understanding is achieved by comparison with random phase approximation calculations for deformed nuclei using for the first time a realistic nucleon-nucleon interaction derived from the Argonne V18 potential with the unitary correlation operator method and supplemented by a phenomenological three-nucleon contact interaction. A wavelet analysis allows one to extract significant scales both in the data and calculations characterizing the fine structure of the GDR. The fair agreement for scales in the range of a few hundred keV supports the surmise that the fine structure arises from ground-state deformation driven by α clustering.

The (N12, C12) charge-exchange reaction at 175 MeV/u was developed as a novel probe for studying the isovector spin giant monopole resonance (IVSMR), whose properties are important for better understanding the bulk properties of nuclei and asymmetric nuclear matter. This probe, now available through the production of N12 as a secondary rare-isotope beam, is exothermic, is strongly absorbed at the surface of the target nucleus, and provides selectivity for spin-transfer excitations. All three properties enhance the excitation of the IVSMR compared to other, primarily light-ion, probes, which have been used to study the IVSMR thus far. The Zr90(N12,C12) reaction was measured and the excitation energy spectra up to about 70 MeV for both the spin-transfer and non-spin-transfer channels were deduced separately by tagging the decay by γ emission from the C12 ejectile. Besides the well-known Gamow-Teller and isobaric analog transitions, a clear signature of the IVSMR was identified. By comparing with the results from light-ion reactions on the same target nucleus and theoretical predictions, the suitability of this new probe for studying the IVSMR was confirmed.

© 2018 American Physical Society. We systematically measured the differential cross sections of inelastic α scattering off self-conjugate A=4n nuclei at two incident energies Eα=130MeV and 386MeV at Research Center for Nuclear Physics, Osaka University. The measured cross sections were analyzed by the distorted-wave Born-approximation (DWBA) calculation using the single-folding potentials, which are obtained by folding macroscopic transition densities with the phenomenological αN interaction. The DWBA calculation with the density-dependent αN interaction systematically overestimates the cross sections for the ΔL=0 transitions. However, the DWBA calculation using the density-independent αN interaction reasonably well describes all the transitions with ΔL=0-4. We examined uncertainties in the present DWBA calculation stemming from the macroscopic transition densities, distorting potentials, phenomenological αN interaction, and coupled channel effects in C12. It was found that the DWBA calculation is not sensitive to details of the transition densities nor the distorting potentials, and the phenomenological density-independent αN interaction gives reasonable results. The coupled-channel effects are negligibly small for the 21+ and 31- states in C12, but not for the 02+ state. However, the DWBA calculation using the density-independent interaction at Eα=386MeV is still reasonable even for the 02+ state. We concluded that the macroscopic DWBA calculations using the density-independent interaction are reliably applicable to the analysis of inelastic α scattering at Eα∼100MeV/u.

In order to study the T-z = +1 -&gt; 0 Gamow-Teller (GT) transitions in the mass A = 26 system, a charge-exchange reaction Mg-26(He-3,t)Al-26 was performed at an incident energy of 140 MeV/nucleon and scattering angle at and near 0 degrees, where T-z is the z component of isospin T defined by (N - Z)/2. In this (p, n)-type reaction, it is expected that GT states with T = 0, 1, and 2 are excited. An energy resolution of Delta E = 23 keV allowed us to study many discrete states. Most of the prominent states showed 0 degrees-peaked angular distributions, which suggested that they are the states excited by Delta L = 0 GT transitions. Candidates of GT states were studied up to an excitation energy E-x = 18.5 MeV. The reduced GT transition strengths, B(GT), were derived assuming the proportionality between cross sections and B(GT) values. Standard B(GT) values were obtained form the Si-26 beta decay, where the mirror symmetry of T-z = +/- 1 -&gt; 0 GT transitions was assumed. The GT strength, as a whole, is divided in two energy regions: the region of up to 8.5 MeV and the higher-energy region of 8.5-12.8MeV, where the strength in the latter region distributed like a resonance. The obtained GT strength distribution is compared with the results of random phase approximation calculations. The T = 2 GT states are expected in the region E-x &gt;= 13.5 MeV. By comparing with the results of (n, p)-type Mg-26(d, He-2)Na-26 and Mg-26(t, He-3)Na-26 reactions, the isospin symmetry of T = 2 GT states is discussed. Owing to the high-energy resolution, we could study the decay widths Gamma for the states in the E-x &gt; 9 MeV region. The T = 2 state at 13.592 MeV is not noticeably wider than the experimental energy resolution. The narrow width of the state is explained in terms of isospin selection rules.

Neutron-proton pairing correlations are investigated in detail via np transfer reactions in N = Z sd-shell nuclei. In particular, we study the cross-section ratio of the lowest 0(+) and 1(+) states as an observable to quantify the interplay between T = 0 (isoscalar) and T = 1 (isovector) pairing strengths. The experimental results are compared to second-order distorted-wave Born approximation calculations with proton-neutron amplitudes obtained in the shell-model formalism using the universal sd-shell interaction B. Our results suggest underestimation of the nonneglible isoscalar pairing strength in the shell-model descriptions at the expense of the isovector channel.

The electric dipole strength distribution in Ca-48 between 5 and 25 MeV has been determined at RCNP, Osaka from proton inelastic scattering experiments at forward angles. Combined with photoabsorption data at higher excitation energy, this enables the first extraction of the electric dipole polarizability alpha(D) (Ca-48) = 2.07(22) fm(3). Remarkably, the dipole response of Ca-48 is found to be very similar to that of Ca-40, consistent with a small neutron skin in Ca-48. The experimental results are in good agreement with ab initio calculations based on chiral effective field theory interactions and with state-of-the-art density-functional calculations, implying a neutron skin in Ca-48 of 0.14-0.20 fm.

Background: The quenching of spin-isospin modes in nuclei is an important field of research in nuclear structure. It has an impact on astrophysical reaction rates and on fundamental processes like neutrinoless double-beta decay. Gamow-Teller (GT) and spin-flip M1 strengths are quenched. Concerning the latter, the J(pi) = 1(+) resonance in the doubly magic nucleus Ca-48, dominated by a single transition, serves as a reference case. Purpose: The aim of the present work is to search for weak M1 transitions in Ca-48 with a high-resolution (p,p') experiment at 295 MeV and forward angles including 0 degrees. and a comparison with results from a similar study using backward-angle electron scattering at low momentum transfers in order to estimate their contribution to the total B(M1) strength in Ca-48. Methods: The spin-M1 cross sections of individual peaks in the spectra are deduced with a multipole decomposition analysis (MDA) and converted to reduced spin-M1 transition strengths by using the unit cross-sectionmethod. For a comparison with electron-scattering results, corresponding reduced B(M1) transition strengths are extracted following the approach outlined in Birkhan et al. [Phys. Rev. C 93, 041302(R) (2016)]. Results: In total, 30 peaks containing a M1 contribution are found in the excitation energy region 7-13 MeV. The resulting B(M1) strength distribution compares well to the electron-scattering results considering different factors limiting the sensitivity in both experiments and the enhanced importance of mechanisms breaking the proportionality of nuclear cross sections and electromagnetic matrix elements for weak transitions as studied here. The total strength of 1.14(7) mu(2)(N) N deduced assuming a nonquenched isoscalar part of the (p,p') cross sections agrees with the (e,e') result of 1.21(13) mu(2)(N) . A bin-wise analysis above 10 MeV provides an upper limit of 1.51(17) mu(2)(N) Conclusions: The present results confirm the previous electron-scattering work that weak transitions contribute about 25% to the total B(M1) strength in Ca-48 and the quenching factors of GT and spin-M1 strength are then comparable in fp-shell nuclei. Thus, the role of meson-exchange currents seems to be negligible in Ca-48, in contrast to sd-shell nuclei.

A high-resolution (He-3,t) charge-exchange experiment at an incident energy of 420 MeV has been performed on the double beta (beta beta) decay nucleus Se-82. A detailed Gamow-Teller (GT(-)) strength distribution in Br-82 has been extracted, which provides information to the beta beta-decay nuclear matrix elements. Three strong and isolated transitions, which are to the 75, 1484 and the 2087 keV states in Br-82, are found to dominate the low-excitation region below approximate to 2.1 MeV. Above 2.1 MeV a sudden onset of a strong GT fragmentation is observed. The degree of fragmentation resembles a situation found in the neighboring A = 76 system (Ge-76), whereas the observed concentration of strength in the three low-lying states is reminiscent of the heavier neighbors Zr-96 and Mo-100. The strong GT transition to the 75 keV (1(+)) state makes Se-82 interesting for solar neutrino detection. The Se-82(nu(e),e(-))Br-82 solar neutrino capture rate in a nonoscillation scenario is therefore evaluated to 668 +/- 12(stat) +/- 60(sys) SNU, and some of the advantages of using selenium for solar neutrino studies are discussed.

In this work we have studied T-z = +2 -&gt; +1, Gamow-Teller (GT) transitions in the Ti-48(He-3, t)V-48 chargeexchange reaction at 140 MeV/nucleon and 0 degrees at the Research Center for Nuclear Physics, Osaka. From the high-resolution facility, consisting of a high-dispersion beamline and the Grand Raiden spectrometer, the spectrum had an energy resolution of 21 keV, among the best achieved. Individual GT transitions were observed and GT strength was derived for each state populated up to an excitation energy of 12 MeV. The total sum of the B(GT) strength observed in discrete states was 4.0, which is 33% of the sum-rule-limit value of 12. The results were compared with the results of shell-model calculations carried out with the GXPF1J interaction. The measured B(GT) distribution was also compared with that obtained in the (He-3, t) charge-exchange reaction on Ti-47. On the assumption of isospin symmetry the beta spectrum of the T-z = -2 nucleus Fe-48 was deduced from the observed spectrum in the Ti-48(He-3, t)V-48 reaction and this predicted spectrum was compared with the measured one.

Inelastic proton scattering at energies of a few hundred million electron volts and extreme forward angles selectively excite the isovector spin-flip M1 (IVSM1) resonance. A method based on isospin symmetry is presented to extract its electromagnetic transition strength from the (p, p') cross sections. It is applied to Ca-48, a key case for an interpretation of the quenching phenomenon of the spin-isospin response, and leads to a M1 strength consistent with an older (e, e') experiment excluding the almost two times larger value from a recent (gamma, n) experiment. Good agreement with electromagnetic probes is observed in Pb-208, suggesting the possibility of extracting systematic information on the IVSM1 resonance in heavy nuclei.

A candidate resonant tetraneutron state is found in the missing-mass spectrum obtained in the double-charge-exchange reaction He-4(He-8, Be-8) at 186 MeV/u. The energy of the state is 0.83 +/- 0.65(stat) +/- 1.25(syst) MeV above the threshold of four-neutron decay with a significance level of 4.9 sigma. Utilizing the large positive Q value of the (He-8, Be-8) reaction, an almost recoilless condition of the four-neutron system was achieved so as to obtain a weakly interacting four-neutron system efficiently.

The electric dipole strength distribution in Sn120 between 5 and 22 MeV has been determined at the Research Center for Nuclear Physics, Osaka, from polarization transfer observables measured in proton inelastic scattering at E0=295 MeV and forward angles including 0°. Combined with photoabsorption data, a highly precise electric dipole polarizability αD(Sn120)=8.93(36)fm3 is extracted. The dipole polarizability as isovector observable par excellence carries direct information on nuclear symmetry energy and its density dependence. The correlation of the new value with the well-established αD(Pb208) serves as a test of its prediction by nuclear energy density functionals. Models based on modern Skyrme interactions describe the data fairly well while most calculations based on relativistic Hamiltonians cannot.

The electric dipole strength distribution in Sn-120 between 5 and 22 MeV has been determined at the Research Center for Nuclear Physics, Osaka, from polarization transfer observables measured in proton inelastic scattering at E-0 = 295 MeV and forward angles including 0 degrees. Combined with photoabsorption data, a highly precise electric dipole polarizability alpha(D)(Sn-120) = 8.93(36) fm(3) is extracted. The dipole polarizability as isovector observable par excellence carries direct information on nuclear symmetry energy and its density dependence. The correlation of the new value with the well-established alpha(D)(Pb-208) serves as a test of its prediction by nuclear energy density functionals. Models based on modern Skyrme interactions describe the data fairly well while most calculations based on relativistic Hamiltonians cannot.

Differential cross sections of isoscalar and isovector spin-M1 (0(+) -&gt; 1(+)) transitions are measured using high-energy-resolution proton inelastic scattering at E-p = 295 MeV on Mg-24, Si-28, S-32, and Ar-36 at 0 degrees-14 degrees. The squared spin-M1 nuclear transition matrix elements are deduced from the measured differential cross sections by applying empirically determined unit cross sections based on the assumption of isospin symmetry. The ratios of the squared nuclear matrix elements accumulated up to E-x = 16 MeV compared to a shell-model prediction are 1.01(9) for isoscalar and 0.61(6) for isovector spin-M1 transitions, respectively. Thus, no quenching is observed for isoscalar spin-M1 transitions, while the matrix elements for isovector spin-M1 transitions are quenched by an amount comparable with the analogous GamowTeller transitions on those target nuclei.

Purpose: Skin toxicity caused by radiotherapy has been visually classified into discrete grades. The present study proposes an objective and continuous assessment method of skin erythema in digital images taken under arbitrary lighting conditions, which is the case for most clinical environments. The purpose of this paper is to show the feasibility of the proposed method. Methods: Clinical data were gathered from six patients who received carbon beam therapy for lung cancer. Skin condition was recorded using an ordinary compact digital camera under unfixed lighting conditions; a laser Doppler flowmeter was used to measure blood flow in the skin. The photos and measurements were taken at 3 h, 30, and 90 days after irradiation. Images were decomposed into hemoglobin and melanin colors using independent component analysis. Pixel values in hemoglobin color images were compared with skin dose and skin blood flow. The uncertainty of the practical photographic method was also studied in nonclinical experiments. Results: The clinical data showed good linearity between skin dose, skin blood flow, and pixel value in the hemoglobin color images; their correlation coefficients were larger than 0.7. It was deduced from the nonclinical that the uncertainty due to the proposed method with photography was 15%; such an uncertainty was not critical for assessment of skin erythema in practical use. Conclusions: Feasibility of the proposed method for assessment of skin erythema using digital images was demonstrated. The numerical relationship obtained helped to predict skin erythema by artificial processing of skin images. Although the proposed method using photographs taken under unfixed lighting conditions increased the uncertainty of skin information in the images, it was shown to be powerful for the assessment of skin conditions because of its flexibility and adaptability. (C) 2015 American Association of Physicists in Medicine.

To study the Gamow-Teller (GT) transitions from the T-z = +1 nucleus Ca-42 to the T-z = 0 nucleus Sc-42, where T-z is the z component of isospin T, we performed a (p, n)-type (He-3, t) charge-exchange reaction at 140 MeV/nucleon and scattering angles around 0 degrees. With an energy resolution of 29 keV, states excited by GT transitions (GT states) could be studied accurately. The reduced GT transition strengths B(GT) were derived up to the excitation energy of 13 MeV, assuming the proportionality between the cross sections at 0 degrees and B(GT) values. The main part of the observed GT transition strength is concentrated in the lowest 0.611-MeV, J(pi) = 1(+) GT state. All the other states at higher energies are weakly excited. Shell-model calculations could reproduce the gross feature of the experimental B(GT) distribution, and random-phase-approximation calculations including an attractive isoscalar interaction showed that the 0.611-MeV state has a collective nature. It was found that this state has all of the properties of a "low-energy super-Gamow-Teller state." It is expected that low-lying J(pi) = 1(+) GT states have T = 0 in the T-z = 0 nucleus Sc-42. However, T = 1 states are situated in a higher energy region. Assuming an isospin-analogous structure in A = 42 isobars, analogous T = 1, 1(+) states are also expected in Ca-42. Comparing the Ca-42(He-3, t)Sc-42 and Ca-42(p, p') spectra measured at 0 degrees, candidates for T = 1 GT states could be found in the 10-12-MeV region of Sc-42. They were all weakly excited. The mass dependence of the GT strength distributions in Sc isotopes is also discussed.

The electric dipole strength distribution in Sn-120 has been extracted from proton inelastic scattering experiments at E-p = 295 MeV and at forward angles including 0 degrees. It differs from the results of a Sn-120(gamma, gamma ') experiment and peaks at an excitation energy of 8.3 MeV. The total strength corresponds to 2.3(2)% of the energy-weighted sum rule and is more than three times larger than what is observed with the (gamma, gamma ') reaction. This implies a strong fragmentation of the E1 strength and/or small ground state branching ratios of the excited 1(-) states. (C) 2015 The Authors. Published by Elsevier B.V.

We have studied the β decay of the Tz=-1,f7/2 shell nuclei Ni54,Fe50,Cr46, and Ti42 produced in fragmentation reactions. The proton separation energies in the daughter Tz=0 nuclei are relatively large (≈4-5 MeV) so studies of the γ rays are essential. The experiments were performed at GSI as part of the Stopped-beam campaign with the RISING setup consisting of 15 Euroball Cluster Ge detectors. From the newly obtained high precision β-decay half-lives, excitation energies, and β branching ratios, we were able to extract Fermi and Gamow-Teller transition strengths in these β decays. With these improved results it was possible to compare in detail the Gamow-Teller (GT) transition strengths observed in beta decay including a sensitivity limit with the strengths of the Tz=+1 to Tz=0 transitions derived from high resolution (3He,t) reactions on the mirror target nuclei at RCNP, Osaka. The accumulated B(GT) strength obtained from both experiments looks very similar although the charge exchange reaction provides information on a broader energy range. Using the "merged analysis" one can obtain a full picture of the B(GT) over the full Qβ range. Looking at the individual transitions some differences are observed, especially for the weak transitions. Their possible origins are discussed.

We have studied the beta decay of the T-z = -1, f(7/2) shell nuclei Ni-54, Fe-50, Cr-46, and Ti-42 produced in fragmentation reactions. The proton separation energies in the daughter T-z = 0 nuclei are relatively large (approximate to 4-5 MeV) so studies of the. rays are essential. The experiments were performed at GSI as part of the Stopped-beam campaign with the RISING setup consisting of 15 Euroball Cluster Ge detectors. From the newly obtained high precision beta-decay half-lives, excitation energies, and beta branching ratios, we were able to extract Fermi and Gamow-Teller transition strengths in these beta decays. With these improved results it was possible to compare in detail the Gamow-Teller (GT) transition strengths observed in beta decay including a sensitivity limit with the strengths of the T-z = +1 to T-z = 0 transitions derived from high resolution (He-3,t) reactions on the mirror target nuclei at RCNP, Osaka. The accumulated B(GT) strength obtained from both experiments looks very similar although the charge exchange reaction provides information on a broader energy range. Using the "merged analysis" one can obtain a full picture of the B(GT) over the full Q(beta) range. Looking at the individual transitions some differences are observed, especially for the weak transitions. Their possible origins are discussed.

Background: The Gamow-Teller response of Ar-40 is important for the use of liquid argon as a medium for neutrino detection. An ambiguity about the Gamow-Teller strength for the excitation of 1(+) states at 2290 and 2730 keV in K-40 results in a significant uncertainty for neutrino capture rates. This ambiguity is caused by the large discrepancy observed between strengths extracted from Ar-40(p, n) charge-exchange data and the transition strengths for the analog transitions studied in the beta decay of Ti-40. Purpose: This study was aimed at resolving the ambiguity between the results from the Ar-40(p, n) charge-exchange and Ti-40 beta-decay data. Method: Shell-model calculations in the sd-pf shell with a new interaction (WBMB-C) were used to study differences between the structure of the transitions from Ar-40 and Ti-40. Distorted-wave Born approximation reaction calculations were used to investigate uncertainties in the extraction of Gamow-Teller strength from the Ar-40(p, n) data. New high-resolution data for the Ar-40(He-3,t) reaction were used to gain further insight into the charge-exchange reaction mechanism and to provide more information to test the validity of the shell-model calculations. Results: The shell-model calculations showed that interference between amplitudes associated with pf and sd components to the low-lying Gamow-Teller transitions, in combination with a difference in Coulomb energy shifts for Ar-40 and Ti-40, can produce the differences on the scale of those observed between the Ar-40 charge-exchange and Ti-40 beta-decay data. In combination with the difference in nuclear penetrability of the (p, n) and (He-3,t) probes, the different contributions from amplitudes associated with transitions in the pf and sd shells are likely also responsible for the observed discrepancy between the ratio of the cross sections for the low-lying 1(+) states in the Ar-40(p, n) and Ar-40(He-3,t) data. Conclusions: On the basis of this study, it is recommended to use Gamow-Teller strengths extracted from the Ar-40(p, n) data, not the Ti-40 beta-decay data, for the calculation of neutrino capture rates. Further theoretical studies are required to achieve a consistent quantitative description for the energy differences between low-lying 1(+) states in K-40 and Sc-40 and the experimentally observed Gamow-Teller strengths.

Background: The electric isovector giant dipole resonance (IVGDR) in Pb-208 has been measured with high energy resolution with the (p, p') reaction under extreme forward angles [A. Tamii et al., Phys. Rev. Lett. 107, 062502 (2011)] and shows considerable fine structure. Purpose: The aim of the present work is to extract scales characterizing the observed fine structure and to relate them to dominant decay mechanisms of giant resonances. Furthermore, the level density of J(pi) = 1(-) states is determined in the energy region of the IVGDR. Methods: Characteristic scales are extracted from the spectra with a wavelet analysis based on continuous wavelet transforms. Comparison with corresponding analyses of B(E1) strength distributions from microscopic model calculations in the framework of the quasiparticle phonon model and the relativistic random phase approximation allows one to identify giant resonance decay mechanisms responsible for the fine structure. The level density of 1(-) states is related to local fluctuations of the cross sections in the energy region of the IVGDR, where contributions from states with other spin parities can be neglected. The magnitude of the fluctuations is determined by the autocorrelation function. Results: Scales in the fine structure of the IVGDR in Pb-208 are found at 80, 130, 220, 430, 640, and 960 keV, and at 1.75 MeV. The values of the most prominent scales can be reasonably well reproduced by the microscopic calculations although they generally yield a smaller number of scales. The inclusion of complex configurations in the calculations changes the E1 strength distributions but the impact on the wavelet power spectra and characteristic scales is limited. The level density of 1(-) states is extracted in the excitation energy range 9-12.5 MeV and compared to a variety of phenomenological and microscopic models. Conclusions: In both models the major scales are already present at the one-particle one-hole level indicating Landau damping as a dominant mechanism responsible for the fine structure of the IVGDR in contrast to the isoscalar giant quadrupole resonance, where fine structure arises from the coupling to low-lying surface vibrations. The back-shifted Fermi gas model parametrization of Rauscher et al., Phys. Rev. C 56, 1613 (1997) describes the level-density data well, while other phenomenological and microscopic approaches fail to reproduce absolute values or the energy dependence or both.

Gamow-Teller (GT) transitions in atomic nuclei are sensitive to both nuclear shell structure and effective residual interactions. The nuclear GT excitations were studied for the mass number A = 42, 46, 50, and 54 "f-shell" nuclei in (He-3, t) charge-exchange reactions. In the Ca-42 -&gt; Sc-42 reaction, most of the GT strength is concentrated in the lowest excited state at 0.6 MeV, suggesting the existence of a low-energy GT phonon excitation. As A increases, a high-energy GT phonon excitation develops in the 6-11 MeV region. In the Fe-54 -&gt; Co-54 reaction, the high-energy GT phonon excitation mainly carries the GT strength. The existence of these two GT phonon excitations are attributed to the 2 fermionic degrees of freedom in nuclei.

We measured the differential cross sections of the O-16(p,d) reaction populating the ground state and several low-lying excited states in O-15 using 198-, 295- and 392-MeV proton beams at the Research Center for Nuclear Physics (RCNP), Osaka University, to study the effect of the tensor interactions in O-16. Dividing the cross sections for each excited state by the one for the ground state and comparing the ratios over a wide range of momentum transfer, we found a marked enhancement of the ratio for the positive-parity state(s). The observation is consistent with large components of high-momentum neutrons in the ground-state configurations of O-16 due possibly to the tensor interactions.

Electric dipole (El) reduced transition probability B(El) of Zr-90 was obtained by the inelastic proton scattering near 0 degrees using a 295 MeV proton beam and multipole decomposition analysis of the angular distribution by the distorted-wave Born approximation with the Hartree-Fock plus random-phase approximation model and inclusion of El Coulomb excitation, and the El strength of the pygmy dipole resonance was found in the vicinity of the neutron threshold in the low-energy tail of the giant dipole resonance. Using the data, we plan to determine the precise dipole polarizability alpha(D) which is defined as an inversely energy-weighted sum value of the elecrric dipole strength. The dipole polarizability is expected to constrain the symmetry energy term of the neutron matter equation of state. Thus systematical measurement of the dipole polarizability is important.

The differential cross sections of the O-16(p,d) reaction populating the ground state and several low-lying excited states in O-15 were measured using 198-, 295- and 392-MeV proton beams at the Research Center for Nuclear Physics (RCNP), Osaka University, to study the effect of the tensor interactions in O-16 Dividing the cross sections for each excited state by the one for the ground state and comparing the ratios over a wide range of momentum transfer, we found a marked enhancement of the ratio for the positive-parity state(s). The observation is consistent with large components of high-momentum neutrons in the ground-state configurations of O-16 due possibly to the tensor interactions.

We pick up two studies on the nuclear responses from the recent experiments of high-resolution proton inelastic scattering at the Research Center for Nuclear Physics, Osaka University; 1) study of the nuclear symmetry and the neutron skin thickness by the measurement of energy electric dipole (E1) response of Pb-208, and 2) study of the tensor correlation in the ground state by the measurement of the spin-M1 responses of even-even self-conjugate nuclei in the sd-shell nuclei.

We are developing a neutron detector with a position resolution better than 3 mm to study the single particle properties of nuclei by the knockout (p, pn) reaction at intermediate energies. We constructed a prototype detector consisting of scintillating fibers and multi-anode photomultiplier tubes (PMTs). A test experiment using 70-MeV proton and 68- and 50-MeV neutron was performed for characterizing its performance. In preliminary results, a position resolution of about 3 mm, is realized, as designed. The resulting separation-energy resolution would be 1 MeV, when using this system at a distance of 2 m from the target for measuring the (p, pn) reaction.

The spectroscopy of deeply bound pionic atoms provides a way to understand the restoration of chiral symmetry breaking at unite density. We have been performing a series of experiments of missing-mass spectroscopy of the (d,He-3) reaction at HIRE to investigate pionic atoms of several Sn isotopes. As a first step, we conducted a pilot experiment to measure deeply bound pionic states of Sn-121 and successfully observed the deeply bound pionic states. In addition to the experiment at RIBF, we are planning the spectroscopy of deeply bound pionic atoms in inverse kinematics and conducted a feasible study by simulations. We showed that by using a deuterium gaseous active target TPC and silicon detectors, the Q-value resolution is about 500 keV (FWHM) and the yield of the pionic Is state is 20 counts/day, indicating the experiment is feasible.