Some Evidence of the Cluster Struture Inside of9Be

High-spin states in $^{22}$Ne

The structure of high-lying states in $^{22}$Ne has been studied using the $^{14}$C($^{12}$C,$\alpha$)$^{22}$Ne reaction at E($^{12}$C)= 44 MeV. The spins were determined by measuring double ($\alpha$,$\alpha$) angular correlations. Selective population of the 9$^-$ and 11$^-$ states at E$_x$=20.1 and 20.7 MeV, respectively, identifies those states as the 9$^-$ and 11$^-$ members of the first $K^{\pi}$ = 0$^-$ band, whose lower members were investigated by a method using inverse kinematics and a thick gas target. The spin and parity of four other new levels were determined to be 9$^-$ (21.5 MeV),12$^+$ (22.1 MeV),9$^-$ (25.0 MeV) and 8$^+$ (22.9 MeV). The two levels 9$^-$ and 12$^+$ may bel…

Study of internal structures of 9,10Be and 10B in scattering of 4He from 9Be

A study of inelastic scattering and single-particle transfer reactions was performed by an alpha beam at 63 MeV on a 9$Be target. Angular distributions of the differential cross sections for the 9Be(4He,4He')9Be*, 9Be(4He,3He)10Be and 9Be(4He,t)10B reactions were measured. Experimental angular distributions of the differential cross sections for the ground state and a few low-lying states were analyzed in the framework of the optical model, coupled channels and distorted-wave Born approximation. An analysis of the obtained spectroscopic factors was performed.

Deep sub-threshold $K^\ast (892)^{\circ}$ production in collisions of Ar + KCl at 1.76 A GeV

pp and ππ intensity interferometry in collisions of Ar+KCl at 1.76A GeV

Results on pp, π+π+, and π-π- intensity interferometry are reported for collisions of Ar+KCl at 1.76$A$~GeV beam energy, studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. The experimental correlation functions as a function of the relative momentum are compared to model calculations allowing the determination of the space-time extent of the corresponding emission sources. The π π source radii are found significantly larger than the pp emission radius. The present radii do well complement the source-size excitation functions of the collision system of size $A+A \simeq 40+40$. The pp source radius at fixed beam energy is found to increase linearly with the cube r…

Electromagnetic Calorimeter for HADES Experiment

Electromagnetic calorimeter (ECAL) is being developed to complement dilep- ton spectrometer HADES. ECAL will enable the HADES@FAIR experiment to mea- sure data on neutral meson production in heavy ion collisions at the energy range of 2-10 AGeV on the beam of future accelerator SIS100@FAIR. We will report results of the last beam test with quasi-monoenergetic photons carried out in MAMI facility at Jo- hannes Gutenberg Universitat Mainz.

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…

Study of the structure of the Hoyle state by refractive α-scattering

α + 12C elastic and inelastic to the Hoyle state (0+ 2, 7.65 MeV) differential cross-sections were measured at the energies 60 and 65 MeV with the aim of testing the microscopic wave function [1] widely used in modern structure calculations of 12C. Deep rainbow (Airy) minima were observed in all four curves. The minima in the inelastic angular distributions are shifted to the larger angles relatively those in the elastic ones, which testify the radius enhancement of the Hoyle state. In general, the DWBA calculations failed to reproduce the details of the cross sections in the region of the rainbow minima in the inelastic scattering data. However, by using the phenomenological density with r…

Cluster Structure of9Be from3He+9Be Reaction

The study of inelastic scattering and multi-nucleon transfer reactions was performed by bombarding a 9Be target with a 3He beam at an incident energy of 30 MeV. Angular distributions for 9Be(3He,3He)9Be, 9Be(3He,4He)8Be, 9Be(3He,7Be)5He, 9Be(3He,6Li)6Li and 9Be(3He,7Li)5Li reaction channels were measured. Cross sections for channels leading to unbound 5He g.s ., 5Li g.s . and 8Be systems were obtained from singles measurements where the relationship between the energy and the scattering angle of the observed stable ejectile is constrained by two-body kinematics. Information on the cluster structure of 9Be was obtained from the transfer channels. It was concluded that cluster transfer is an …

Verification of Electromagnetic Calorimeter Concept for the HADES spectrometer

The HADES spectrometer currently operating on the beam of SIS18 accelerator in GSI will be moved to a new position in the CBM cave of the future FAIR complex. Electromagnetic calorimeter (ECAL) will enable the HADES@FAIR experiment to measure data on neutral meson production in heavy ion collisions at the energy range of 2-10 A GeVon the beam of the new accelerator SIS100. Calorimeter will be based on 978 massive lead glass modules read out by photomultipliers and a novel front-end electronics. Secondary gamma beam with energies ranging from 81 MeV up to 1399 MeV from MAMI-C Mainz facility was used to verify selected technical solutions. Relative energy resolution was measured using modules…

The 2n-Evaporation Channels In the Fusion of [sup 4,6]He with [sup 206,208]Pb

Excitation functions of the reaction products were measured for the reactions induced by 4,6He projectiles on 206,208Pb targets, leading to the same compound nucleus. This was accomplished by using the stacked‐foil‐activation technique. The identification of the reaction products (accumulated in the Pb targets) was done by their radioactive alp ha decays. The excitation functions for the 2n evaporation channels were obtained at energies below the sub‐Coulomb barrier region. A large value of the fusion cross section was observed in the case of the reaction induced by the weakly bound 6He projectile.

Peculiarities in fragment mass distribution in the 238U + 40Ar (243 MeV) reaction

A pronounced fine structure (FS) in the form of distinct peaks was observed in neutron gated mass spectra from the decay of the 278110 composite system produced in the reaction 238U + 40Ar (243 MeV) at an initial excitation energy E * > 70 MeV. The FS peaks are located in the vicinity of mass numbers 70-80, 100, and 130, which correspond to those of magic nuclei (clusters). In the data there is also evidence for a new type of decay -- collinear cluster tripartition of an excited nucleus.

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…

Study of the 2n-evaporation channel in the 4,6He+206,208Pb reactions

Abstract Excitation functions of the reaction products were measured for the reactions induced by 4,6 He projectiles on 208,206 Pb targets, leading to the same compound nucleus. This was accomplished by using the stacked-foil activation technique. The identification of the reaction products (accumulated in the Pb targets) was done by their radioactive α -decays. The excitation functions for the various products were obtained at energies including the sub-Coulomb barrier region. A large value of the fusion cross section was observed in the case of the reaction induced by the weakly bound 6 He projectile.

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

12C + 12C large angle elastic scattering at 240 MeV

Abstract The measurement of the differential cross sections of the 12C + 12C and the 13C + 12C elastic scattering are carried out at the 12C energy 240 MeV and the 13C energy 250 MeV to solve some interpretation problem of the 12C + 12C scattering data. Is it possible that the 1st Airy minimum in 12C + 12C scattering data is missing? Our analysis shows that the positions of the 1st Airy minima obtained in former measurements are confirmed.

High-resolution scattering experiments at the K130 cyclotron in Jyväskylä

Abstract An experimental setup for nuclear reaction studies induced by light and heavy ions is described. It consists of a versatile Large Scattering Chamber equipped with two rotating tables for mounting detectors. A dedicated beam diagnostic system is used to monitor the energy spectrum of the beam on target. The system provides the necessary feedback for tuning of the K-130 cyclotron to reduce the energy spread of the accelerated beam by at least a factor of 3 down to about 0.3% of the nominal energy while maintaining beam currents around 20 pnA. At lower beam currents a 0.1% energy spread can be achieved. This improvement makes a significant impact on the scope of reaction studies possi…

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

Fragment mass distribution in superasymmetric region in proton-induced fission of U and Th

Fission fragment mass distributions down to super-asymmetric mass region and both pre- and post-scission neutron multiplicity for238U(p,fission) reaction atEp = 20, 35, 50, 60 MeV and for232Th(p, fission) reaction atEp = 50, 60 MeV were measured using HENDES set-up. The results indicate enhancement for super-asymmetric mass division at intermediate excitation energies.

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

Fine structure in fragment mass-energy distribution from 238U+40Ar (275 MeV)

Existence of a new feature in fragment mass-energy distribution is reported. Careful analysis of the data obtained in the reaction 238U + 40Ar (275 MeV) shows that small but statistically significant ripples visible already in the gross mass spectrum come from extended and regular 2D patterns in the TKE vs. mass matrix. Intensity distributions of these patterns coincide with the location of heavy clusters such as 78Ni, 108Mo, or 132Sn. Presumably, the observed patterns show the dominant trajectories in the elongation vs. mass-asymmetry space of the decaying system. This information, unknown in the past, can shed a new light even on the previously well-studied reactions.

Investigation of the elastic and inelastic scattering of He-3 from Be-9 in the energy range 30-60 MeV

We have measured the differential cross-sections for the elastic as well as inelastic scattering populating the 2.43[Formula: see text]MeV [Formula: see text] excited state in [Formula: see text] using [Formula: see text] beams at energies of 30, 40 and 47[Formula: see text]MeV on a [Formula: see text] target. The experimental results for the elastic scattering were analyzed within the framework of the optical model using the Woods–Saxon and double-folding potentials. The theoretical calculations for the concerned excited states were performed using the coupled-channel method. The optimal deformation parameters for the excited states of [Formula: see text] nucleus were extracted.

Rotational band in 12C based on the Hoyle state

t. α + 12C inelastic differential cross-sections were measured at the energies 65 and 110 MeV. A new broad state at 13.75 MeV was observed. Its spin-parity has been determined as 4+ and the diffraction radius of the corresponding L = 4 transition is ~ 0.8 fm larger than that of the excitation of the 4+, 14.8 MeV level. The 13.75 MeV state was considered to be the third member of the rotational band based on the Hoyle state. peerReviewed

Some Evidence of the Cluster Struture Inside of 9Be

Angular distributions of protons, deuterons, tritons and alpha-particles emitted from the reactions in the 2H+9Be-system at Elab=19.5 MeV were measured with an aim to shed light on the internal cluster structure of 9Be and the study of possible cluster transfer of 5He. The analyses suggest a significant contribution of five-nucleon transfer in the reaction channel 9Be(d,4He)7Li. peerReviewed

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…