Possibility of ~5He emission in neutron induced reactions

There are some statistical model codes[1—4] as the evaluation tool that have been long and widely used to set up neutron data library below 20 MeV, which is the most important energy region in the application of nuclear engineering. The emitted particles considered in these codes mentioned above are neutrons, protons, as well as the compos-ite particles, such as deuterons, tritons, 3He and alpha particles. These emitted particles and nuclei can be treated as the nucleon or stable clusters. H…     

Theoretical studies of proton capture reactions in A～25 proton-rich nuclei

The direct proton capture and resonance proton capture properties of stellar reactions 22Mg(p,γ)23Al and 26Si(p,γ)27P are studied by employing a mean-field potential obtained from the Skyrme-Hartree-Fock(SHF) model.Calculations with the SHF potential reproduce well the loosely-bound structure of the ground states as well as the widths of the resonant states in these nuclei.With the obtained potential we estimate the reaction rates of direct proton capture and resonance proton capture to nuclei 23Al and 27P....     

Production of dN? dibaryon in kaon induced reactions

In this paper,we propose to investigate the d_NΩ dibaryon production in the K^-p→■ process by utilizing a kaon beam with a typical momentum of approximately 10 GeV,which may be available at COMPASS,OKA@U-70,and SPS@CERN.The cross sections for K^-p→■ are estimated,and in particular,the magnitude of the cross sections is evaluated to be several hundred nanobarns at P_K=20 GeV.Considering that the d_NΩdibaryon dominantly decays into ΞA and Ξ∑,we als...     

Spin-photon Entanglement in Spontaneous Emission

The two-pathway decay, spin-photon entanglement, and spontaneous generated spin coherence in a Lambdatype three-level system can be understood in a unified picture in terms of quantum entanglement of the electron spin, the photon polarization, and the photon waveform. Within such a unified picture, the spontaneous emission can be controlled to present a designated effect by external field, optical excitation, and quantum measurement. Various experiments are proposed to implement such control, with some of them already realized.     

Nuclear-like effects in proton–proton collisions at high energy

We show that several effects considered nuclear effects are not nuclear in the sense that they do not only occur in nucleus–nucleus and hadron–nucleus collisions but, as well, they are present in hadron–hadron (proton–proton) collisions. The matter creation mechanism in hh, hA and AA collision is always the same. The p _T suppression of particles produced in large multiplicity events compared to low multiplicity events, the elliptic flow and the Cronin effect are predicted to occur in pp collisions at LHC energies as a consequence of the high density partonic medium obtained.     

Microscopic calculation of proton capture reactions in the mass 60–80 region and its astrophysical implications

Microscopic optical potentials obtained by folding the DDM3Y interaction with the densities from the Relativistic Mean-Field approach have been utilized to evaluate S-factors of low-energy (p, γ) reactions in the mass 60–80 region and to compare with experiments. The Lagrangian density FSU Gold has been employed. Astrophysical rates for important proton capture reactions have been calculated to study the behaviour of rapid proton nucleosynthesis for waiting point nuclei with mass less than A = 80.     

Cross sections for proton induced reactions on 41K and for the reaction 62Ni(α, p)65Cu

Excitation functions have been measured for ⁶²Ni(α, p)⁶⁵Cu in the energy range 6.5–9.0 MeV, for ⁴¹K(p, α)³⁸Ar in the range 0.8–2.6 MeV, for ⁴¹K(p, γ)⁴²Ca, ⁴¹K(p, αγ)³⁸Ar, ⁴¹K(p, nγ)⁴¹Ca, and ⁴¹K(p, p'γ)⁴¹ in the range 0.6–4.0 MeV, and for ⁴¹K(p, n)⁴¹Ca from threshold to 3.0 MeV. Cross sections have been extracted from the data and these are compared with statistical-model calculations based on global optical model parameters. Alternative parameter sets have been tried for the ⁶²Ni(α, p)⁶⁵Cu data and published data for ⁶²Ni(α, γ)⁶⁶Zn and ⁶²Ni(α, n)⁶⁵Zn, and both these and the global parameters have been used in statistical-model calculations of ⁶⁵Cu(p, γ)⁶⁶Zn, ⁶⁵Cu(p, n)⁶⁵Zn and ⁶⁵Cu(p, α)⁶²Ni cross sections, which are compared with published data for these reactions. Both the global and the alternative parameters lead to very good agreement with experiment for all six reactions. Alternative parameters have been tried for the ⁴¹K + p reactions also. The global parameters lead to agreement to within a factor of 2 and the alternative parameters lead to agreement to within a factor of 1.3. The ⁴¹K + p alternative parameters are used in calculations of ⁴¹Ca(n, γ)⁴²Ca, ⁴¹Ca(n, p)⁴¹K and ⁴¹Ca(n, α)³⁸Ar cross sections, and these and the experimental ⁴¹K + p data are used in calculations of thermonuclear reaction rates under stellar conditions for the ⁴¹Ca + n and ⁴¹K + p reactions.     

Transverse spin asymmetries for W-production in proton–proton collisions

We study parity-even and parity-odd polarization observables for the process pp→l^±X$pp\to l^{\pm }X$, where the lepton comes from the decay of a W-boson. By using the collinear twist-3 factorization approach, we consider the case when one proton is transversely polarized, while the other is either unpolarized or longitudinally polarized. These observables give access to two particular quark–gluon–quark correlation functions, which have a direct relation to transverse momentum dependent parton distributions. We present numerical estimates for RHIC kinematics. Measuring, for instance, the parity-even transverse single spin correlation would provide a crucial test of our current understanding of single spin asymmetries in the framework of QCD.     

Neutron to proton cross section ratios in neutrino and antineutrino charged current reactions forE ν<30 GeV

Using the freon filled bubble chamber SKAT at the Serpukhov accelerator we study event charge distributions in neutrino and antineutrino charged current reactions in the (anti)neutrino energy region from 3–30 GeV. We derive from the data the total cross section ratios of reactions on neutrons to reactions on protonsR _ν=2.24±0.18 and \(R_{\bar v} = 0.43\) in agreement with the predictions of the quark parton model. These values agree also with other experimental results at different energies. For neutrino reactions we study additionally the differential distributions in Bjorken variablesx andy.     

Hα Emission Imaging during Supersonic Molecular Beam Injection by CCD Photograph

There are several fuelling methods for tokamak plasma： pellet injection （PI）, gas puffing （GP）, neutral beam injection （NBI） and supersonic molecular beam injection （SMBI） .SMBI has been created in the Southwestern Institute of Physics, China.     

Λ-Hypernucleus formation in proton-nucleus reactions

We study the production of hyperons inp + A reactions within the BUU transport approach including elastic N rescattering and extract the sticking probabilities and hypernucleus formation cross sections as a function of bombarding energy and target mass. At 1.5 GeV about 25% of the hyperons are found to be bound in case of heavy nuclei like²³⁸U leading to large cross sections for-hypernuclei. The respective hypernuclei show broad distributions in excitation energy, momentum and angular momentum. The decay of the hyperon in case of heavy targets is found to be almost entirely due to nonmesonic decay channels, i.e.N NN processes.Supported by BMFT, GSI, Forschungszentrum Jülich and the Polish Committee for Scientific Research under Grant no. PB2593/2/91     

Synthesis and properties of even-even nuclei with Z=114−116 produced in 48Ca induced reactions

In the irradiation of targets made from enriched ²⁴⁴Pu and ²⁴⁸Cm isotopes with beam doses of 1.5×10¹⁹ and 2.3×10¹⁹, respectively, the detector array situated in the focal plane of the gas-filled separator registered heavy atoms of new elements undergoing sequential α decays terminated by spontaneous fission. The time of the decay chains is approximately 1 min. Decay properties of the synthesized nuclei are consistent with the consecutive α decays originating from the parent nuclides ²⁸⁸114 and ²⁹²116 produced with the cross section of about 0.5 picobarn. Comparison of T _SF and T _α values for the nuclei with Z=110 and 112 with those obtained earlier for more light isotopes of these elements points to an enhanced stability of heavy nuclei with an increase in the neutron number. The α-decay energies Q _α, measured experimentally in the chains $116 \underrightarrow {\alpha _1 } 114 \underrightarrow {\alpha _2 } 112 \underrightarrow {\alpha _3 } 110$ , are compared with-theoretical predictions of different nuclear models. From this it follows that the theoretical models predicting the decisive influence of the nuclear structure on the stability of superheavy elements are well-founded not only qualitatively but in some sense also quantitatively. Some preliminary data, obtained in the first experiment aimed at the synthesis of element 118 in the reaction ²⁴⁹Cf+⁴⁸Ca, are presented in the paper. The prospects of further investigations in the field of superheavy nuclei are discussed briefly.     

Excitation of isomeric 1h 11/2 states in nuclear reactions induced by γ rays and neutrons and in beta decay

Isomeric ratios were measured for N=81 isotones (¹³⁵Xe, ¹³⁷Ba, ¹³⁹Ce, ¹⁴¹Nd, ¹⁴³Sm). In the experiment reported here, μ _ν ≤3±10^? J ^π=11/2^? isomers were excited in (n, γ) and (γ, n) reactions and in the β ⁺ decay of ¹³⁹Pr and ¹⁴¹Pm. In order to determine the reaction yields, use was made of the activation method involving measurement of the gamma-ray spectra of reaction products. It is found that, in the same reactions, isomeric ratios are different for isotones characterized by different atomic numbers Z. Isomeric ratios were calculated with the spectra of low-lying levels and radiative-transition probabilities established on the basis of the quasiparticle-phonon model. Good agreement between the experimental and calculated values of isomeric ratios is obtained for all isotopes invesigated here. The dependence of isomeric ratios on the atomic number Z of a nucleus is explained by the difference of reaction energies, which leads to different probabilities of excitation of activation levels through which the isomers being considered are populated.     

On the space-time difference of proton and composite particle emission in central heavy-ion reactions at 400 A · MeV

Small-angle correlations of pairs of nonidentical light charged particles produced in central collisions of heavy ions in the A = 100 mass region at a beam energy of 400 A · MeV are investigated with the FOPI detector system at GSI Darmstadt. The difference of longitudinal correlation functions with the relative velocity parallel and anti-parallel to the center-of-mass velocity of the pair in the central source frame is studied. This method allows extracting the apparent space-time differences of the emission of the charged particles. Comparing the correlations with results of a final-state interaction model delivers quantitative estimates of these asymmetries. Time delays as short as 1~fm/c or - alternatively - source radius differences of a few tenth fm are resolved. The strong collective expansion of the participant zone introduces not only an apparent reduction of the source radius but also a modification of the emission times. After correcting for both effects a complete sequence of the space-time emission of p, d, t, ³He, ! particles is presented for the first time.