Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · nucl-ex/0312011

Photoproduction of eta-mesic 3He

M. Pfeiffer·J. Ahrens·J. R. M. Annand·R. Beck·G. Caselotti·S. Cherepnya·K. Föhl·L. S. Fog·D. Hornidge·S. Janssen·V. Kashevarov·R. Kondratiev·M. Kotulla·B. Krusche·J. C. McGeorge·I. J. D. MacGregor·K. Mengel·J. G. Messchendorp·V. Metag·R. Novotny·M. Rost·S. Sack·R. Sanderson·S. Schadmand·A. Thomas·D. P. Watts
View original source ↗Read source document ↗Export metadata ↓

Abstract

The photoproduction of eta-mesic 3He has been investigated using the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI. The total inclusive cross section for the reaction gamma+3He->eta+X has been measured for photon energies from threshold to 820 MeV. The total and angular differential coherent eta cross sections have been extracted up to energies of 745 MeV. A resonance-like structure just above the eta production threshold with an isotropic angular distribution suggests the existence of a resonant quasi-bound state. This is supported by studies of a competing decay channel of such a quasi-bound eta-mesic nucleus into pi^0+p+X. A binding energy of (-4.4+-4.2) MeV and a width of (25.6+-6.1) MeV is deduced for the quasi-bound eta-mesic state in 3He.

Explore related subjects

nucl-ex

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M. Pfeiffer, J. Ahrens, J. R. M. Annand, R. Beck, G. Caselotti, S. Cherepnya, K. Föhl, L. S. Fog, D. Hornidge, S. Janssen, V. Kashevarov, R. Kondratiev, M. Kotulla, B. Krusche, J. C. McGeorge, I. J. D. MacGregor, K. Mengel, J. G. Messchendorp, V. Metag, R. Novotny, M. Rost, S. Sack, R. Sanderson, S. Schadmand, A. Thomas, D. P. Watts. 2004-06-28. Photoproduction of eta-mesic 3He. https://doi.org/10.1103/physrevlett.92.252001

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

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↗
arXiv2026

Investigation of Medium Modifications to $^{12}$C Structure Functions in the Resonance Region

We present results from a high precision experimental study of the nuclear modification of the longitudinal ($F_L$) to transverse ($F_1$) structure function ratio for bound nucleons in the resonance region. The inclusive electron scattering cross sections were measured in Jefferson Lab Experimental Hall C on carbon and deuterium nuclei for a large range of kinematics, allowing for separations of the longitudinal and transverse structure functions to be performed at a range of four-momentum transfer values $0.5 \le Q^2 \le$ 3.75 GeV$^2$. In contrast to the significant body of measurements of the nuclear modification of the $F_2$ structure function in the deep inelastic scattering region, there is very little on $F_L$ and $R = F_L / 2xF_1$ in the region of the nucleon resonances. In this paper we present measurements of the nuclear effect on $R$ for $^{12}$C ($R_C$) relative to deuterium ($R_D$). These results indicate regions in which in $R_C>R_D$, requiring that the nuclear modifications be different in all three structure functions, $F_2$, $F_1$ and $F_L$.

nucl-ex↗