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Register a new userTotal and differential cross sections of $eta$-production in proton-deuteron fusion for excess energies between $Q_eta=13;text{MeV}$ and $Q_eta=81;text{MeV}$
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New data on both total and differential cross sections of the production of $eta$ mesons in proton-deuteron fusion to ${}^3text{He},eta$ in the excess energy region $13.6;text{MeV}leq Q_eta leq 80.9;text{MeV}$ are presented. These data have been obtained with the WASA-at-COSY detector setup located at the Forschungszentrum Julich, using a proton beam at 15 different beam momenta between $p_p = 1.60;text{GeV}/c$ and $p_p = 1.74;text{GeV}/c$. While significant structure of the total cross section is observed in the energy region $20;text{MeV}lesssim Q_eta lesssim 60;text{MeV}$, a previously reported sharp variation around $Q_etaapprox 50;text{MeV}$ cannot be confirmed. Angular distributions show the typical forward-peaking that was reported elsewhere. For the first time, it is possible to study the development of these angular distributions with rising excess energy over a large interval.
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New high precision total and differential cross sections are reported for the $dpto {}^3textrm{He},eta$ reaction close to threshold. The measurements were performed using the magnetic spectrometer ANKE, which is an internal fixed target facility at the COSY cooler synchrotron. The data were taken for deuteron beam momenta between $3.14641~textrm{GeV}/c$ and $3.20416~textrm{GeV}/c$, which corresponds to the range in excess energy $Q$ for this reaction between $1.14~textrm{MeV}$ and $15.01~textrm{MeV}$. The normalization was established through the measurement in parallel of deuteron-proton elastic scattering and this was checked through the study of the $dpto {}^3textrm{He},pi^0$ reaction. The previously indicated possible change of sign of the slope of the differential cross sections near the production threshold, which could be explained by a rapid variation of the $s$- and $p$-wave interference term, is not confirmed by the new data. The energy dependence of the total cross section and the $90^{circ}$ slope parameter are well explained by describing the final state interaction in terms of a complex Jost function and the results are significant in the discussion of $eta$-mesic nuclei. In combination with recently published WASA-at-COSY data [P. Adlarson $et, al.$, Phys. Lett. B 782, 297 (2018)], a smooth variation of the slope parameter is achieved up to an excess energy of $80.9~textrm{MeV}$.
New precise unpolarised differential cross sections of deuteron-proton elastic scattering have been measured at 16 different deuteron beam momenta between $p_d = 3120.17;textrm{MeV}/c$ and $p_d =3204.16;textrm{MeV}/c$ at the COoler SYnchrotron COSY of the Forschungszentrum Julich. The data, which were taken using the magnetic spectrometer ANKE, cover the equivalent range in proton kinetic energies from $T_p = 882.2;textrm{MeV}$ to $T_p = 918.3;textrm{MeV}$. The experimental results are analysed theoretically using the Glauber diffraction model with accurate nucleon-nucleon input. The theoretical cross section at $T_p = 900;textrm{MeV}$ agrees very well with the experimental one at low momentum transfers $|t| <0.2;(textrm{GeV}/c)^2$.
Differential cross sections for deuteron breakup $^{1}H(d, pp)n$ reaction were measured for a large set of 243 geometrical configurations at the beam energy of 80 MeV/nucleon. The cross section data are normalized by the luminosity factor obtained on the basis of simultaneous measurement of elastic scattering channel and the existing cross section data for this process. The results are compared to the theoretical calculations modeling nuclear interaction with and without taking into account the three-nucleon force (3NF) and Coulomb interaction. In the validated region of the phase space both the Coulomb force and 3NF play an important role in a good description of the data. There are also regions, where the improvements of description due to including 3NF are not sufficient.
The charge exchange of vector polarised deuterons on a polarised hydrogen target has been studied in a high statistics experiment at the COSY-ANKE facility at a deuteron beam energy of Td = 726 MeV. By selecting two fast protons at low relative energy E_{pp}, the measured analysing powers and spin correlations are sensitive to interference terms between specific neutron-proton charge-exchange amplitudes at a neutron kinetic energy of Tn ~ 1/2 Td =363 MeV. An impulse approximation calculation, which takes into account corrections due to the angular distribution in the diproton, describes reasonably the dependence of the data on both E_{pp} and the momentum transfer. This lends broad support to the current neutron-proton partial-wave solution that was used in the estimation.
The neutron total cross sections $sigma_{tot}$ of $^{16,18}$O, $^{58,64}$Ni, $^{103}$Rh, and $^{112,124}$Sn have been measured at the Los Alamos Neutron Science Center (LANSCE) from low to intermediate energies (3 $leq E_{lab} leq$ 450 MeV) by leveraging waveform-digitizer technology. The $sigma_{tot}$ relative differences between isotopes are presented, revealing additional information about the isovector components needed for an accurate optical-model description away from stability. Digitizer-enabled $sigma_{tot}$-measurement techniques are discussed and a series of uncertainty-quantified dispersive optical model (DOM) analyses using these new data is presented, validating the use of the DOM for modeling light systems ($^{16,18}$O) and systems with open neutron shells ($^{58,64}$Ni and $^{112,124}$Sn). The valence-nucleon spectroscopic factors extracted for each isotope reaffirm the usefulness of high-energy proton reaction cross sections for characterizing depletion from the mean-field expectation.
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