Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · nucl-ex/0105002

Spin-triplet final-state dominance in the pp -> pn pi+ reaction at 492 MeV

V. Abaev·M. Buescher·S. Dymov·M. Hartmann·A. Kacharava·V. I. Komarov·V. Koptev·V. Kurbatov·S. Mikirtychiants·M. Nekipelov·A. Petrus·H. Stroeher·Yu. N. Uzikov·C. Wilkin·S. Yaschenko
View original source ↗Read source document ↗Export metadata ↓

Abstract

The near-forward cross section for the pp -> pn pi^+ reaction has been measured at 492 MeV by using the large acceptance ANKE magnetic spectrometer placed at an internal target position of the storage ring COSY-Juelich. Protons and pions emitted near zero degrees were detected in coincidence, and those with theta_pi <= 2 degrees and theta_p <= 2.5degrees were subjected to detailed analysis. Under these conditions, the excitation energy in the np system was below 3 MeV over the measured momentum range. This is the region of the np final-state-interaction peak, which was measured with a resolution of a fraction of an MeV. The shape of the peak allows one to conclude that the fraction of final spin-singlet np pairs is below about 10%. By using the results of scattering theory, this limit is confirmed through a comparison with the cross section for pp -> d pi^+. The smallness of the singlet contribution is consistent with trends seen in lower energy data.

Explore related subjects

nucl-ex

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

V. Abaev, M. Buescher, S. Dymov, M. Hartmann, A. Kacharava, V. I. Komarov, V. Koptev, V. Kurbatov, S. Mikirtychiants, M. Nekipelov, A. Petrus, H. Stroeher, Yu. N. Uzikov, C. Wilkin, S. Yaschenko. 2001-09-13. Spin-triplet final-state dominance in the pp -> pn pi+ reaction at 492 MeV. https://doi.org/10.1016/s0370-2693(01)01229-1

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Precise and accurate nuclear electric quadrupole moment of $^{223}$Ra from molecular spectroscopy

Nuclear electric quadrupole moments of unstable isotopes are commonly extracted from laser spectroscopy of the atomic hyperfine structure, where the accuracy is limited to the several-percent level by the available electric-field-gradient (EFG) calculations. In this study, we determine the spectroscopic quadrupole moment of $^{223}$Ra (half-life $t_{1/2} = 11.4$ d) from hyperfine-resolved collinear resonance ionization spectroscopy of the radioactive molecule $^{223}$Ra$^{19}$F. The $X\,^2Σ^+$ electronic ground state of RaF provides a large axial EFG at the radium nucleus that can be calculated with relativistic coupled-cluster theory to sub-percent accuracy. Together with a three-fold improvement in spectral resolution over previous fast-beam measurements of radioactive molecules, this yields $Q_s = +1.211(7)_\mathrm{stat}(2)_\mathrm{syst}(5)_\mathrm{theo}\,e\mathrm{b}$ for $^{223}$Ra with a total uncertainty of 0.73%, approximately three times better than atomic and ionic determinations. This result demonstrates that molecular spectroscopy can provide access to the electromagnetic structure of unstable nuclei with a precision competitive with, and in favorable cases better than, atomic spectroscopy, and may thus be envisioned for studies beyond the limitations of current radioactive-atom experiments.

nucl-ex↗
arXiv2026

Characterizing $\pT$-differential Radial-Flow Fluctuations in Au+Au Collisions at FAIR with a Multi-Phase Transport Model

We report the first predictions of the transverse-momentum ($\pT$)-differential radial-flow fluctuation observable, $\vzpT$, in Au+Au collisions at the top SIS100 energy, $\snn=4.9$~GeV, which will be available at the FAIR accelerator complex. Radial flow and its fluctuations are studied for different centrality intervals and reference-$\pT$ selections to investigate the properties and robustness of the calculated long-range correlation. $\vzpT$ displays a characteristic evolution from negative values at low $\pT$ to positive values at higher $\pT$. The integrated $v_0$, obtained with different reference-$\pT$ intervals, follows a common trend, with an approximately inverse-square-root dependence on the inclusive charged-particle multiplicity ($\nch$). The $\vzpT$ signal changes little when the pseudorapidity gap is varied between 0.2 and 0.8, or when the edges of the reference-$\pT$ interval are varied, in the bulk region. For identified particles, the pion and proton $\vzpT$ are ordered at low $\pT$, qualitatively similar to the mass ordering seen at higher energies. However, unlike at higher collision energies, $\vzpT$ does not exhibit constituent-quark number scaling, so the results do not support an interpretation in terms of partonic collectivity. The results are also in partial contradiction with the behavior of hadronic elliptic flow in these low-energy collisions. These results provide constraints on the evolution of radial correlations toward lower collision energies and motivate comparisons with complementary observables to clarify their connection to collective dynamics.

nucl-ex↗
arXiv2026

Cumulative protons and pions at the intermediate energies in the FRAGM experiment

One of the important research objectives of the FRAGM experiment operating at the TWAC heavy-ion accelerator-storage complex was the study of particle production in the cumulative region. Differential cross sections were measured for the production of pions - resulting from the fragmentation of carbon nuclei at an energy of 3.2 GeV/nucleon, as well as protons with energy range from 300 to 2000 MeV/nucleon at an angle of 3.5 degrees relative to the incident ion beam. The parameterization of cumulative effect used in experiments investigating nucleus-nucleus interactions is discussed. It is shown, that the energy dependencies of these parameters are analogous to those observed in nucleon-nucleus interactions and indicate the presence of nuclear scaling behavior.

nucl-ex↗