0000000000219648
AUTHOR
N. Burtebaev
The study of the 12C states from the reaction 11B(3He, d)12C
The experiment was done to study 11B(3He, d)12C reaction with energy E(3He)=25 MeV. The aim of the experiment is to determine the properties of 12C states at high excitation energies and in particular to verify which of the conflicting spin-parity assignments of the 13.35 MeV state (2− or 4−) should be assigned. Behavior of the experimental angular distribution and also the DWBA calculation correspond to spin parity 4− for 13.35 MeV state. peerReviewed
Spin-parity of the 13.35 MeV state and high-lying states around 20 MeV in excitation energy in $^{12}$C nucleus
Study of the $^{11}$B($^{3}$He,d)$^{12}$C reaction at incident $^{3}$He energy E$_{lab}$ = 25 MeV has been performed at the K-130 cyclotron at the University of Jyv\"askyl\"a, Finland. Differential cross sections have been measured for the 13.35 MeV state and for the states with excitation energy around 20 MeV. The data were analyzed with the DWBA method. A tentative assignment, 4$^{-}$, is given for the state at 13.35 MeV. For the state at 20.98 MeV, the spin-parity 3$^{-}$ and the isospin T = 0 are assigned for the first time. Our model description of the broad state at 21.6 MeV is consistent with the previous assignments of isospin T = 0 and spin-parity of 2$^{+}$ and 3$^{-}$. The excite…
Neutron halos in the excited states of 12B
The differential cross sections of the 11B(d,p) 12B reaction leading to formation of the 1+ ground state and the 0.95-MeV 2+, 1.67-MeV 2−, 2.62-MeV 1−, 2.72-MeV 0+, and 3.39-MeV 3− excited states of 12B are measured at Ed = 21.5 MeV. The analysis of the data is carried out within the coupled-reaction-channels method for the direct neutron transfer and the Hauser-Feshbach formalism of the statistical compound-nucleus model. The spectroscopic factors, asymptotic normalization coefficients, and rms radii of the last neutron in all states studied are deduced. The existence of the neutron halos in the 1.67-MeV 2− and 2.62-MeV 1− states is found, consistent with the earlier published data. New in…
Neutron halos in excited states of 12 B
An experiment was done to search for states with a neutron halo in 12 B. The measurements were carried out at the cyclotron of the University of Jyvaskyla (Finland) using Large Scattering Chamber (LSC). The idea of the work was to search for two states with the expected neutron halo, 1¯ and 2¯. Differential cross sections with excitation of 12 B states, including abovementioned states, were observed. The preliminary calculations on halo radii by the method of asymptotic normalization coefficients for the 2¯ and 1¯ states which are in a discrete spectrum gave following values: 5.6 fm and 7.4 fm, which is much larger than the radius of the valence neutron in the ground state. But strictly the…
Possible neutron and proton halo structure in the isobaric analog states of A=12 nuclei
The differential cross sections of the 11B(3He,d)12C reaction leading to formation of the 0+ ground state and the 15.11-MeV 1 +, 16.57-MeV 2−, and 17.23-MeV 1− excited states of 12C are measured at Elab=25 MeV. The analysis of the data is carried out within the coupled-reaction-channels method for the direct proton transfer to the bound and unbound states. The rms radii of the last proton in all states studied are determined. A comparison of the rms radii of the 12B, 12C, and 12N nuclei in the isobaric analog states (IASs) with isospin T=1 determined by different methods allows us to arrive at a conclusion that these nuclei in the 1− excited states at Ex=2.62, 17.23, and 1.80 MeV, respectiv…
Possible neutron and proton halo structure in the isobaric analog states of A=12 nuclei
The differential cross sections of the $^{11}\mathrm{B}(^{3}\mathrm{He},d)^{12}\mathrm{C}$ reaction leading to formation of the ${0}^{+}$ ground state and the 15.11-MeV 1 ${}^{+}$, 16.57-MeV ${2}^{\ensuremath{-}}$, and 17.23-MeV ${1}^{\ensuremath{-}}$ excited states of $^{12}\mathrm{C}$ are measured at ${E}_{\text{lab}}=25$ MeV. The analysis of the data is carried out within the coupled-reaction-channels method for the direct proton transfer to the bound and unbound states. The rms radii of the last proton in all states studied are determined. A comparison of the rms radii of the $^{12}\mathrm{B}, ^{12}\mathrm{C}$, and $^{12}\mathrm{N}$ nuclei in the isobaric analog states (IASs) with isosp…
STATES OF 12N WITH ENHANCED RADII
The differential cross sections of the $^{12}$C($^3$He,t)$^{12}$N reaction leading to formation of the 1$^+$ (ground state), 2$^+$(0.96 MeV), 2$^{-}$(1.19 MeV), and 1$^{-}$(1.80 MeV) states of $^{12}$N are measured at $E$($^3$He)=40 MeV. The analysis of the data is carried out within the modified diffraction model (MDM) and distorted wave Born approximation (DWBA). Enhanced $rms$ radii were obtained for the ground, 2$^{-}$(1.19 MeV), and 1$^{-}$(1.80 MeV) states. We revealed that $^{12}$B, $^{12}$N, and $^{12}$C in the IAS with T=1, and spin-parities 2$^{-}$ and 1$^{-}$ have increased radii and exhibit properties of neutron and proton halo states.
Spectroscopy of exotic states of 13C
The differential cross-sections of the elastic and inelastic 13C + α scattering were measured at E (α) = 65 MeV. The radii of the states: 8.86 (1/2¯), 3.09 (1/2+ ) and 9.90 (3/2¯) MeV were determined by the Modified diffraction model (MDM). The radii of the first two levels are enhanced relatively that of the ground state of 13C, confirming the suggestion that the 8.86 MeV state could be an analogue of the Hoyle state in 12C and the 3.09 MeV state has a neutron halo. No enhancement of the radius of the 9.90 MeV state was observed. peerReviewed
States of 13C with abnormal radii
Differential cross-sections of the elastic and inelastic 13C + α scattering were measured at E(α) = 90 MeV. The root mean-square radii () of 13C nucleus in the states: 8.86 (1/2−), 3.09 (1/2+) and 9.90 (3/2−) MeV were determined by the Modified diffraction model (MDM). The radii of the first two levels are enhanced compared to that of the ground state of 13C, confirming the suggestion that the 8.86 MeV state is an analogue of the Hoyle state in 12C and the 3.09 MeV state has a neutron halo. Some indications to the abnormally small size of the 9.90 MeV state were obtained. peerReviewed
Cluster states in 11B
The differential cross-sections of the elastic and inelastic 11B + α scattering was measured at E(α) = 65 MeV. The analysis of the data by Modified diffraction model (MDM) showed that the RMS radii of the 11B state 3/2-, E* = 8.56 MeV is ~ 0.6 fm larger than that of the ground state. The 12.56 MeV state was not observed contrary to the predictions of the α-condensate model. The 13.1 MeV state was excited with the angular momentum transfer L = 4 confirming its belonging to the rotational band with the 8.56 MeV state as a head. peerReviewed
Asymptotic normalization coefficients and halo radii of12B in the excited states
We present the results of measurements and analysis of the differential cross sections of the 11 B(d, p )12 B reaction leading to formation of the 1+ ground state and the 0.953-MeV 2+ , 1.674-MeV 2− , 2.621-MeV 1− , 2.723-MeV 0+ , 3.389-MeV 3− excited states of 12 B at Ed = 21.5 MeV. The analysis of the data was carried out within the coupled-reaction-channels method for the direct neutron transfer and the Hauser-Feshbach formalism of the statistical compound-nucleus model. We deduced the spectroscopic factors, asymptotic normalization coefficients, and rms radii of the last neutron in all states studied. The existence of the neutron halos in the 1.674-MeV 2− and 2.621-MeV 1− states was fou…
Neutron halos in the excited states of B12
The differential cross sections of the $^{11}\mathrm{B}(d,p)\phantom{\rule{0.16em}{0ex}}^{12}\mathrm{B}$ reaction leading to formation of the ${1}^{+}$ ground state and the 0.95-MeV ${2}^{+}$, 1.67-MeV ${2}^{\ensuremath{-}}$, 2.62-MeV ${1}^{\ensuremath{-}}$, 2.72-MeV ${0}^{+}$, and 3.39-MeV ${3}^{\ensuremath{-}}$ excited states of $^{12}\mathrm{B}$ are measured at ${E}_{d}$ = 21.5 MeV. The analysis of the data is carried out within the coupled-reaction-channels method for the direct neutron transfer and the Hauser-Feshbach formalism of the statistical compound-nucleus model. The spectroscopic factors, asymptotic normalization coefficients, and rms radii of the last neutron in all states stu…