Missing-mass spectroscopy of the C12(p,d) reaction near the η′ -meson production thresho

Abstract

Excitation-energy spectra of 11 C nuclei near the η -meson production threshold have been measured by missing-mass spectroscopy using the 12 C(p,d) reaction. A carbon target has been irradiated with a 2.5 GeV proton beam supplied by the synchrotron SIS-18 at GSI to produce η meson bound states in 11 C nuclei. Deuterons emitted at 0 • in the reaction have been momentum-analyzed by the fragment separator (FRS) used as a high-resolution spectrometer. No distinct structure due to the formation of η -mesic states is observed although a high statistical sensitivity is achieved in the experimental spectra. Upper limits on the formation cross sections of η -mesic states are determined, and thereby a constraint imposed on the η -nucleus interaction is discussed.

Mass Modifications of Light Mesons in Nuclear Matter with the Three Flavor Extended Linear Sigma Model

“…The grand potential (or equivalently the effective action) has been obtained by one-loop of the nucleon with the meson mean fields in Eq. (20), and the "ground state" of the system has been determined by solving the gap equations with respect to φ N , φ S , andω N in Eq. (23), respectively.…”

“…Then, another experiment called E16 experiment is planned at J-PARC. Besides, the η mesic nuclei experiments at GSI [18][19][20] and at the University of Bonn [21][22][23][24], and pp → ppη reaction experiment at the COSY accelerator complex [25] have been operated, regarding the investigation of the change of U (1) A axial anomaly in nuclear matter. Another η mesic nuclei experiments is ongoing at SPring-8 [26] (see Ref.…”

Exploration of Nuclear Structure Along the Proton-unbound Argon and Chlorine Isotopes

“…The details of the experimental setup can be found in Refs. [1,3,11], here just a brief description is given. The secondary beam of 620 A MeV 31 Ar with the intensity of 50 ions per second was transported by the first half of FRS to the thick 9 Be target.…”

“…Here, one can raise the question about the limits of existence of such nuclear structure. In order to investigate this on the neutrondeficient side of the nuclear chart, we performed detailed investigations of argon and chlorine proton-unbound isotopes [1][2][3]. All three articles report studies done via trajectories measurement of the in-flight decay products performed at the fragment-separator and spectrometer FRS at GSI, Darmstadt.…”

“…In the theoretical paper [2], we perform predictions for the lightest quasistationary systems to be 26 Ar and 25 Cl in the corresponding isotopic chains, done on the basis of cluster models and experimental systematics obtained in [1]. The article [3] is devoted to previously unobserved 30 Ar and its "subsystem" 29 Cl. One of the interesting results of those investigations is the new estimation of the two-proton separation energy S 2p = +6(34) keV for the 31 Ar ground state.…”