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In the PANDA experiment of the FAIR project, it is proposed to use internal targets based on the hydrogen isotopes that provide a monodisperse regime of flow generation of solid spherical pellets with the diameter from 15–40 µm with the frequency from several tens of to several hundred kilohertz. The process for generating the pellets in such facilities includes the cooling, liquefying, and disintegration into drops of the liquid hydrogen jet directed vertically downwards; freezing of the jet when expiring with acceleration into vacuum; and its transport through the vacuum path into the region of interaction with the antiproton beam. For the effective control of the systems of the setup and for the adjustment of generation of pellets, an automatization and control system is developed combining the devices for measurement and control of pellet parameters (temperature, pressure, hydrogen flow, and piezoelectric generator frequency) and the optical diagnostics in a unified computational network. For data exchange between the devices, the TCP/IP Sockets and Modbus TCP protocols are used. [ABSTRACT FROM AUTHOR]

The ratios of the cross sections for ϕ-meson production induced by 2.83-GeV protons on Cu, Ag, and Au nuclei to the respective cross section for C nuclei were measured at the ANKE-COSY facility in the momentum range of 0.6-1.6 GeV/ c and the angular range of 0°-8°. The product ϕ mesons were identified by their decay ϕ → K K. The procedure used to separate kaon pairs was described in detail, and all sources of the background and their contribution to the resulting error in the values found for the above cross-section ratios were analyzed. The A dependence of the cross section for ϕ-meson production was shown to obey the A law. The total width of the ϕ meson at a normal nuclear density was extracted from a comparison of the measured cross-section ratios with the results of calculations based on two theoretical models. The resulting width value exceeds substantially both the vacuum width and the width expected in the absence of the nuclear-matter effect on the properties of the ϕ meson. [ABSTRACT FROM AUTHOR]

The total cross-section for the dd $ \rightarrow$ 4He K+ K- reaction has been measured at a beam momentum of 3.7GeV/ c, corresponding to an excess energy of 39MeV, which is the maximum possible at the Cooler Synchrotron COSY-Jülich. A deuterium cluster-jet target and the ANKE forward magnetic spectrometer, placed inside the storage ring, have been employed in this investigation. We find a total cross-section of $ \sigma_{{{\rm tot}}}^{}$ < 14 pb, which brings into question the viability of investigating the dd $ \rightarrow$ 4He a0(980) reaction as a means of studying isospin violation. [ABSTRACT FROM AUTHOR]

A combined analysis of the published data on the pp → dK +¯0 reaction at excess energies of 47.4MeV and 104.7MeV is presented that takes into account final-state interactions in both the K +¯0 and ¯0 d channels. The strong attraction of the antikaons with nucleons, already noted for the pp → ppK + K - reaction, leads here to very different ¯0 d and K+d distributions, with the former being dominantly in an s -wave and the latter in a p -wave. Evidence is also found from the K +¯0 distributions for the production of the a 0 +(980) scalar resonance. The inclusion of both final-state interactions improves the description of the energy dependence of the pp → dK +¯0 total cross-section. [ABSTRACT FROM AUTHOR]

The production of ω-mesons in the pp → ppω reaction has been investigated with the COSY-ANKE spectrometer for excess energies of 60 and 92MeV by detecting the two final protons and reconstructing their missing mass. The large physical background was subtracted using an event-by-event transformation of the proton momenta between the two energies. Differential distributions and total cross-sections were obtained after careful studies of possible systematic uncertainties in the overall ANKE acceptance. The results are compared with the predictions of theoretical models. Combined with data on the φ-meson, a more refined estimate is made of the Okubo-Zweig-Iizuka rule violation in the φ/ω production ratio. [ABSTRACT FROM AUTHOR]

The reaction pp → dK +¯ has been investigated at excess energies Q = 47.4 and 104.7MeV above the K +¯ threshold at COSY Jülich. Coincident dK+ pairs were detected with the ANKE spectrometer, and subsequently ∼ 2000 events with a missing ¯ invariant mass were identified, which fully populate the Dalitz plot. The joint analysis of invariant mass and angular distributions reveals s-wave dominance between the two kaons, in conjunction with a p-wave between the deuteron and the kaon pair, i.e. K¯ production via the a 0 +(980) channel. Integration of the differential distributions yields total cross-sections of σ( pp → dK +¯) = (38±2stat±14syst)nb and (190±4stat±39syst)nb for the low and high Q value, respectively. [ABSTRACT FROM AUTHOR]

The reaction pp → dπ + η has been measured at a beam energy of T p = 2.65 GeV ( p p = 3.46 GeV/ c) using the ANKE spectrometer at COSY-Julich. The missing-mass distribution of the detected dπ + pairs exhibits a peak around the η mass on top of a strong background of multipion pp → dπ +( nπ) events. The differential cross section d 4 σ/ dΩd dΩ π + dp d dp π + for the reaction pp → dπ + η has been determined model independently for two regions of phase space. Employing a dynamical model for the a production allows one then to deduce a total cross section of σ( pp → da → dπ + η) = 1.1 ± 0.3stat ± 0.7syst µb for the production of π + η via the scalar a (980) resonance and σ( pp → dπ + η) = 3.5 ± 0.3stat ± 1.0syst µb for the nonresonant production. Using the same model as for the interpretation of recent results from ANKE for the reaction $$pp \to dK^ + \bar K^0 $$ , the ratio of the total cross sections is $$\sigma (pp \to d(K^ + \bar K^0 )_{L = 0} )/\sigma (pp \to da_0^ + \to d\pi ^ + \eta ) = 0.029 \pm 0.008_{stat} \pm 0.009_{syst} $$ , which is in agreement with branching ratios in the literature. [ABSTRACT FROM AUTHOR]

We present predictions for the K-α scattering length obtained within the framework of the multiple-scattering approach. Evaluating the pole position of the K-α scattering amplitude within the zero-range approximation, we find a loosely bound K-α state with a binding energy of ER = - 2,..., - 7 MeV and a width ΓR = 11,..., 18 MeV. We propose to measure the K-α scattering length through the final-state interaction between the α and K--meson produced in the reaction dd↦α K+ K-. It is found that the K-α invariant-mass distribution from this reaction at energies near the threshold provides a new tool to determine the s-wave K-α scattering length. [ABSTRACT FROM AUTHOR]

The production of K+-mesons inpA(A= D, C, Cu, Ag, Au) collisions has been investigated at the COoler SYnchrotron COSY-Jülich for beam energiesTp = 1.0-2.3 GeV. Double differential inclusivepC cross-sections at forward angles ?{K^+}<12° as well as the target mass dependence of the K+ momentum spectra have been measured with the ANKE spectrometer. Far below the freeNNthreshold atTNN = 1.58 GeV the spectra reveal a high degree of collectivity in the target nucleus. From the target mass dependence of the cross-sections at higher energies, the repulsive in-medium potential of the K+-mesons can be deduced. UsingpNcross-section parameterisations from the literature and our measuredpD data we derive a cross-section ratio s(pn?K+ X)/s(pp?K+ X) ~ (3-4). [ABSTRACT FROM AUTHOR]

The first measurement of the pn → dω total cross-section has been achieved at mean excess energies Q &assymp; 28 and 57MeV by using a deuterium cluster-jet target. The momentum of the fast deuteron was measured in the ANKE spectrometer at COSY-Jülich and that of the slow ‘spectator’ proton (psp) from the pd → pspdω reaction in a silicon telescope placed close to the target. The cross-sections lie above those measured for pp → ppω but seem to be below theoretical predictions. [ABSTRACT FROM AUTHOR]

Using an effective Lagrangian approach as well as the Quark-Gluon Strings Model, we analyze near-threshold production of a0(980)-mesons in the reaction NN → dK &Kmacr; as well as the background of non-resonant K &Kmacr;-pair production. We argue that the reaction pp → dK+ &Kmacr;0 at an energy release Q ≤ 100MeV is dominated by the intermediate production of the a0(980)-resonance. At larger energies the non-resonant K+ &Kmacr;0-pair production — where the kaons are produced in a relative P-wave — becomes important. The effects of final-state interactions are evaluated in a unitarized scattering length approach and found to be in the order of a 20% suppression close to threshold. Thus, in present experiments at the Cooler Synchrotron COSY-Jülich for Q ≤ 107 MeV the a0+ signal can reliably be separated from the non-resonant K+ &Kmacr;00 background. [ABSTRACT FROM AUTHOR]

: Results of a first experiment on (K+p) and (K+d) correlations from proton-carbon (pC) and proton-deuteron (pd) interactions at beam energies above and much below the threshold for elementary kaon production in nucleon-nucleon reactions ( TNN = 1580 MeV) are discussed. These data, obtained with the ANKE spectrometer at COSY-Jülich, provide first direct evidence for K+ production via the two-step mechanism and an indication for a cluster mechanism. It is shown that both processes contribute significantly in pC collisions at 1200 MeV, while they are strongly suppressed at 2300 MeV and also in pd-interactions at 1344 MeV. It is emphasized that the underlying kinematics can be exploited to distinguish between these reaction mechanisms. [ABSTRACT FROM AUTHOR]

We consider near-threshold a[sub 0](980)-meson production in πN and NN collisions. An effective Lagrangian approach with one-pion exchange is applied to analyze different contributions to the cross section for different isospin channels. The Reggeon exchange mechanism is also evaluated for comparison. The results from πN reactions are used to calculate the contribution of the a[sub 0] meson to the cross sections and invariant KK mass distributions of the reactions pp → pnK[sup +]K[sup 0] and pp → ppK[sup +]K[sup –]. It is found that the experimental observation of a[sub 0][sup +] mesons in the reaction pp → pnK[sup +]K[sup 0] is much more promising than the observation of a[sub 0][sup 0] mesons in the reaction pp → ppK[sup +]K[sup –]. Effects of isospin violation in the reactions pN → da[sub 0], pd → [sup 3]He([sup 3]H)a[sub 0], and dd → [sup 4]Hea[sub 0], which are induced by a[sub 0](980)–f[sub 0](980) mixing, are also analyzed.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The ω resonance production and its π0γ decay in pA reactions close to threshold is considered within the Intranuclear Cascade (INC) model. The π0γ invariant-mass distribution shows two components which correspond to the ω decay “inside” and “outside” the nucleus, respectively. The “inside” component is distorted by medium effects, which introduce a mass shift as well as collisional broadening for the ω-meson and its decaying pion. The relative contribution of the “inside” component is analyzed in detail for different kinematical conditions and nuclear targets. It is demonstrated that a measurement of the correlation in azimuthal angle between the π0 and γ momenta allows to separate events related to the “inside”ω decay from different sources of background when uncorrelated π0's and γ's are produced. [ABSTRACT FROM AUTHOR]

We investigate the reactions π N↦ a0 N and pp↦ da0 + near threshold and at medium energies. An effective Lagragian approach and the Regge pole model are applied to analyze different contributions to the cross-section of the reaction π N↦ a0 N. These results are used to calculate the differential and total cross-sections of the reaction pp↦ da0 + within the framework of the two-step model in which two nucleons produce an a0-meson via π-meson exchange and fuse to a deuteron. The necessity of new measurements on a0 production and branching fractions (of its decay to the K and πη channels) is emphasized for clarifying the a0 structure. Detailed predictions for the reaction pp→ da0 + are presented for the energy regime of the proton synchrotron COSY-Jülich. [ABSTRACT FROM AUTHOR]

The reactions pn → dω) and pn → dφ) are investigated near the corresponding thresholds. The S-wave amplitudes are calculated within the two-step model described by a triangle graph with π, ρ, and ω) mesons in the intermediate state. The cross sections for the reactions pn → dω) and pn → dφ) are predicted to be significantly larger than the cross sections for the corresponding reactions pp → ppω) and pp → ppφ) at the same values of the c.m. excess energy Q. The phi-to-omega yield ratio is found to be (34 ± 10) x 10[sup -3]. [ABSTRACT FROM AUTHOR]

We explore the possibility to measure the elastic and inelastic ω N cross section in p+ d→ d+ω+ psp and p+ A reactions. Our studies indicate that the elastic scattering cross sections can be determined for ω momenta above 1 GeV/c in p+ d reactions by gating on high proton spectator momenta whereas the ω N absorption cross section down to low relative ω momenta is most effectively studied in p+ A reactions at beam energies 2.0–2.7 GeV. [ABSTRACT FROM AUTHOR]

The production of K and π mesons and protons in pBe collisions at T =2.9 GeV has been studied at the ITEP proton synchrotron. Ejectiles with a momentum of p=545 MeV/c were observed under an emission angle ϑ=17°. The detectors which have been developed for the identification of kaons out of a six orders of magnitude more intense background of pions and protons are described. A cross-section ratio dσ /d Ωd p: d σ /d Ωd p: dσ/d Ωd p of (1±0.34):(85±1):(31±1) has been measured. Normalization with existing pion data yields an invariant differential cross section E·dσ /d p=(3.1±1.2) mbGeVcsr and a total cross section of σ( pBe)=(3.7±1.5) mb. These cross sections are compared with existing data and theoretical predictions. The A dependence of K production in the few-GeV range is analyzed. [ABSTRACT FROM AUTHOR]

K-meson production in proton-nucleus interactions at projectile energies up to 15 GeV is studied. As a first step the available data on K-meson production in pp interactions are compared with different parametrizations and results of model calculations. Because of considerable uncertainties in the current descriptions of the energy dependence of the elementary K cross section a new parametrization is suggested. Experimental data on K production in p A collisions are analyzed in the framework of the Rossendorf-Collision and folding models. Satisfactory descriptions of the momentum spectra at forward angles are achieved. From an analysis of the A dependence it can be concluded that K mesons are well suited to investigate final-state interactions for particles interacting strongly with the residual nucleus. Furthermore, we propose experimental studies on K production close to threshold. Such measurements are particularly sensitive to contributions from secondary processes or from multi-nucleon interactions. [ABSTRACT FROM AUTHOR]

Deuteron formation in proton-nucleus reactions due to the coalescence mechanism with final-state interaction between nucleons is discussed in order to establish the kinematical region of the validity of this approach. The experimental data on fast deuteron production in proton-nucleus collisions at bombarding energies above 3 GeV are analyzed. It is shown that most experimental results were obtained for deuteron momenta below the critical limit of the coalescence model. It is discussed to which extent further experimental studies could help to identify contributions from the coalescence mechanism and to get better understanding of the fast deuteron-production process. [ABSTRACT FROM AUTHOR]

We analyzed the K production at projectile energies below the free nucleon-nucleon threshold in proton-nucleus collisions and studied the contribution from different reaction channels to this process. It was shown that the secondary pion-nucleon ( π+N→Λ+K) channel significantly prevails over the direct ( p+N→Λ+N+K) one. The momentum and angular K spectra were calculated in the framework of different production channels in order to propose experimental measurements which allow to distinguish the mechanisms discussed. We also studied K d correlations and considered the deuteron reabsorption in the nuclear medium as well as the fast deuteron background. The features of K p correlations related to the different production channels were analyzed as well. [ABSTRACT FROM AUTHOR]

New data on the production of single neutral pions in the pd→3 He π0 reaction are presented. For fifteen proton beam momenta between pp=1.60 GeV/c and pp=1.74 GeV/c, differential cross sections are determined over a large fraction of the backward hemisphere. Since the only previous systematic measurements of single-pion production at these energies were made in collinear kinematics, the present work constitutes a significant extension of the current knowledge on this reaction. Even this far above the production threshold, significant changes are found in the behaviour of the angular distributions over small intervals in beam momentum. [ABSTRACT FROM AUTHOR]

We present predictions for the K-α scattering length obtained within the framework of the multiple-scattering approach. Evaluating the pole position of the K-α scattering amplitude within the zero-range approximation, we find a loosely bound K-α state with a binding energy of ER = - 2,..., - 7 MeV and a width ΓR = 11,..., 18 MeV. We propose to measure the K-α scattering length through the final-state interaction between the α and K--meson produced in the reaction dd↦α K+ K-. It is found that the K-α invariant-mass distribution from this reaction at energies near the threshold provides a new tool to determine the s-wave K-α scattering length. [ABSTRACT FROM AUTHOR]