Search results for "Cross Section"
showing 10 items of 3111 documents
Measurement of Evaporation Residue and Fission Cross Sections of the Reaction 30Si + 238U at Subbarrier Energies
2007
Effects of the prolate deformation of 238 U on fusion were studied in the reaction 30 Si + 238 U at bombarding energies close to the Coulomb barrier. The fission (capture) cross sections were measured at the JAEA tandem accelerator to see the enhancement of the cross sections in the subbarrier energy due to the lower Coulomb barrier in the collisions of projectile at the polar sides of 238 U. In order to obtain the direct evidence for complete fusion, evaporation residue cross sections were measured at UNILAC of GSI. At the subbarrier energy of Ec.m. = 133.0 MeV, where only polar collisions to 238 U occur, we measured three spontaneously fissioning nuclei which we assigned to the isotope 26…
Precise Measurement of the e+e−→π+π−J/ψ Cross Section at Center-of-Mass Energies from 3.77 to 4.60 GeV
2017
The cross section for the process e(+)e(-)-> pi(+) pi(-) J/psi is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using 9 fb(-1) of data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of (222.0 +/- 3.1 +/- 1.4) MeV/ c(2) and a width of (44.1 +/- 4.3 +/- 2.0)MeV, while the second one has a mass of (4320.0 +/- 10.4 +/- 7.0)MeV/c(2) and a width of (101.4(- 19.7)(+25.3) +/- 10.2) MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the Y(4260) resonance reported by previous experiments. The precisi…
Investigation of the Dipole Response in Exotic Nuclei – Experiments at the LAND-R$^3$B Setup
2012
We present experimental results on the electromagnetic excitation of neutron-rich nickel isotopes, making use of the (RB)-B-3-LAND setup at GSI. Exotic beams were produced at approximately 500 MeV/u and their reactions were studied in inverse kinematics. Integral cross sections for Ni-58 are discussed and compared to previous data, providing a validation of our experimental method. The El excitation-energy distribution of the unstable Ni-68 is presented as well, showing an excess in cross section in the 1n decay channel when compared only with a typical Giant Dipole Resonance.
Observation of D+→f0(500)e+νe and Improved Measurements of D→ρe+νe
2019
Using a data sample corresponding to an integrated luminosity of 2.93 fb(-1) recorded by the BESIII detector at a center-of-mass energy of 3.773 GeV, we present an analysis of the decays D-0 -> ...
Unpolarized and polarized beam sources
1991
The cross sections of photon-induced nuclear processes were usually studied with the aid of a bremsstrahlung beam produced by fast electrons hitting a suitable radiator. Such bremsstrahlung radiation contains photons of all energies from zero up to the kinetic energy of the incoming electrons and so the desired cross section had to be deduced from the integral yield by taking the bremsstrahlung spectrum of the photon beam from the theory. In this section we shall show that this method can produce significant systematic errors in the absolute value of the cross sections due to the lack of a precise knowledge of the bremsstrahlung spectrum.
Recent Hadronic Cross Section Measurements from BABAR
2019
New hadronic cross sections measured by the BABAR experiment are presented: e+e−→ π+π−π0π0, e+ e−→ π+π−η, and the kaonic channels e+e−→ KS KLπ0 , KS KLπ0π0 , KS KLη, KS K±π+π0 , KS K±π+η.
Many Body Modes of Excitation in Heavy Ion Collisions
1989
The one step excitation of two particle holes in heavy ion collisions is shown to be an important channel in the reaction. Pion production has to compete against this new channel, not present in the NN free reaction, and is reduced sensibly. The effective NN cross section is increased leading to a more effective stopping of the nucleons.
Precise Measurement of the e+e− → π+π−J/ψ Cross Section at Center-of-Mass Energies from 3.77 to 4.60 GeV
2020
The cross section for the process e(+)e(-)-> pi(+) pi(-) J/psi is measured precisely at center-of-mass energies from 3.77 to 4.60 GeV using 9 fb(-1) of data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of (222.0 +/- 3.1 +/- 1.4) MeV/ c(2) and a width of (44.1 +/- 4.3 +/- 2.0)MeV, while the second one has a mass of (4320.0 +/- 10.4 +/- 7.0)MeV/c(2) and a width of (101.4(- 19.7)(+25.3) +/- 10.2) MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the Y(4260) resonance reported by previous experiments. The precisi…
Stellar(n,γ)Cross Section ofNi62
2005
The 62Ni(n,gamma)63Ni(t(1/2)=100+/-2 yr) reaction plays an important role in the control of the flow path of the slow neutron-capture (s) nucleosynthesis process. We have measured for the first time the total cross section of this reaction for a quasi-Maxwellian (kT=25 keV) neutron flux. The measurement was performed by fast-neutron activation, combined with accelerator mass spectrometry to detect directly the 63Ni product nuclei. The experimental value of 28.4+/-2.8 mb, fairly consistent with a recent calculation, affects the calculated net yield of 62Ni itself and the whole distribution of nuclei with 62<A<90 produced by the weak s process in massive stars.