10.2172/10158865

Phys.Lett.B

New experimental results for polarization transfer, κ 0 and the analyzing power, T 20 , in 12 C ( d , p ) X at 0° are present. The measurements have been performed at the Dubna polarized deuteron facility. At high intrinsic momenta of the proton in the deuteron ( k ⩾300 MeV/ c ) the behaviour of these observables is in disagreement with the impulse approximation predictions based on realistic NN-potentials. The data are compared with calculations of some other models predicting the high k behaviour of κ 0 and T 20 .

Nucl.Instrum.Meth.A

A calorimeter module was fabricated using profiled lead plates and scintillating fibers with diameter 1 mm and attenuation length about 80 cm. The absorber-to-fiber volume ratio was 1.17 and the module average radiation length X 0 ⋍ 1.05 cm . The energy resolution of the module was investigated using the electron beams of U-70 at Serpukhov and of the SPS at CERN in the energy range 5–70 GeV. The energy resolution at θ = 3° (the angle between the fiber axis and the beam direction) may be expressed by the formula σ E (%) = 13.1 E ⊕ 1.7 . The energy resolution was also simulated by Monte Carlo and good agreement with the experiment has been achieved.

10.2172/10124115

Nucl. Instrum. Meth. A

A new method of function minimization is developed and a new code (called FUMIVI) is created. Its main features are: i) regular functions of arbitrary structure can be minimized, ii) when minimizing χ 2 -like functions or functionals of a more general case one can use the linearization method, and in case of degeneration FUMIVI may automatically switch to accurate calculation of the second derivatives matrix, iii) nonlinear regular constraints of arbitrary type can be used, iv) both analytical and numerical calculation of the derivatives are possible. The new code was extensively tested both with model and real events of the experiment on rare K-meson decays.

Nucl. Instrum. Meth. A

A number of long scintillator counters employing UPS 923A and NE 114 plastic scintillators seen by a single photomultiplier were tested using cosmic muons. These counters have suitable dimensions to be used in large arrays in a proton supercollider experiment. The efficiency for m.i.p. was excellent in all cases. The yield of UPS 923A was found to be by about 25% higher than NE 114, while the attenuation length was approximately the same.

Phys.Lett.B

A search for Ks0→e+e− decay was performed by means of a 624-channel lead glass shower hodoscope and a set of proportional chambers. Neutral kaons were obtained in the quasibinary charge exchange reaction. A new upper limit of 2.8×10 −6 at 90% C.L. for the branching ratio is obtained.

J. Phys. A

Based on the Maslov complex germ theory, a method of constructing the quasi-classical spectral series for the Dirac operator is proposed. The case when the corresponding relativistic Hamiltonian system is non-integrable and it admits a family of invariant two-dimensional stable Lagrangian tori containing the focal points is considered. The resulting quantization conditions for the above family generalize the Bohr-Sommerfeld-Maslov conditions and include new additional characteristics. The quasi-classical asymptotics obtained are regular over the full classically allowed domain. They also form an asymptotically complete and orthonormal set. Examples which use the proposed technique of the quasi-classical quantization are analysed.

Nucl. Phys. A

The double strangeness production has been observed in two final states of annihilation of antiprotons at momentum less than 0.9 GeV/ c on Xe nuclei: K + K + X (8 events) and K + K 0 ΛX (6 events). The probabilities of the reaction p Xe → K + K + X vary from 2 · 10 −5 (at rest) up to 7 · 10 −5 (in flight). The reaction p Xe → K + K 0 ΛX is observed only in flight with probability 3 · 10 −4 . The properties of the observed reactions are similar to those resulting from the cascade process with production of Ξ hyperon: p N → K ∗ −K ∗ , K ∗ → Kπ, −K ∗ N → ΞK, ΞN → ΛΛ . The new upper limit on the production probability of the stable H ( S = −2) dibaryon in the reaction Xe → K + K + H(H → Σ − p)X was obtained to be < 2 · 10 − (90% C . L .).

Phys.Lett.B

In the experiment 272±49 atoms consisting of π + and π + − mesons were observed. The atoms were produced in a Ta target by 70 GeV protons and π + and π − mesons were detected from the atom break-up in the same target.

Phys.Scripta

A universal facility is in preparation for the study of particle production in proton-nucleus reactions below the nucleon-nucleon threshold. The device will be located at the internal target position TP2 at COSY-J?lich and will consist of three dipole magnets. This 0? Facility will separate ejectiles from the circulating proton beam and allow momentum and angle analysis both for positively and negatively charged particles. A major goal of the experimental program is the investigation of the K+-meson production at projectile energies below the NN threshold. The detector concept for these studies is described and also an overview over further planned experiments is given.

Phys.Lett.B

Total cross sections for the reaction π + d → pp have been measured for incident pion energies T π =26.5, 28.5, 30.5, 32.5 and 39.5 MeV. The data are in good agreement with previous experiments. There is some indication of a peculiarity in the energy dependence of the total cross section near incident pion energy T π =30 MeV.

Nucl.Phys.B Proc.Suppl.

Phase II detector fabrication for the International Germanium Experiment is in progress. Sources of background observed during Phase I are discussed. Cosmogenic 7 Be is measured in germanium. Radium contamination, presumably in electroformed copper, is reported.

Mod. Phys. Lett. A

The possibility of using the bremsstrahlung reaction in proton-proton interactions as a new tool for searching and investigating the narrow, exotic 6-quark(di-nucleon) resonances is suggested and discussed.

Phys.Lett.B

The differential cross sections for antiproton elastic scattering on 4 He at 192.8 MeV/ c are measured. The annihilation cross section σ a = (377.6 ± 8.0) mb, the elastic cross section σ el = (206.3 ± 6.6) mb and the total p 4 He interaction cross section σ tot = (583.9 ± 10.4) mb are determined. The ratio of the real to imaginary part of the forward p 4 He amplitude is found: π =−0.17± 0.33 0.24 . Partial wave analysis reveals that the S, P and D waves are essential in this energy region.

Nucl. Phys. A

Recent experimental results in antinucleon-nucleus interaction obtained by the OBELIX collaboration at LEAR are presented. Preliminary results concerning the total antineutron-nucleus annihilation cross section at low energy are reported. They represent the first complete set of measurements on medium and heavy nuclei available in the momentum region below 300 MeV/c. A new measurement of the exotic one-meson annihilation at rest p d → π − p (Pontecorvo reaction) with the better statistics and precision up to now, is reported. Finally, the measurement

Nucl. Phys. A

Antinucleon-nucleus annihilations into two-body final states containing only one or no meson are unusual annihilations (Pontecorvo reactions), practically unexplored experimentally, with the exception of the channel p d → π − p , for which only two low-statistics measurements exist. Their physical interest lies in the possibility of exploring small-distance nuclear dynamics, in which an important role can be played by non-nucleonic degrees of freedom. A new measurement of the p d → π − p reaction rate at rest, performed with the OBELIX spectrometer at LEAR, with the best statistics up to now and a careful evaluation of systematic effects is reported, together with a critical analysis of the existing theoretical models. The measured branching ratio, which confirms the previous results, can represent a reference point for the studies in the field.

Phys.Rev.A

The simultaneous measurement of the spatial coordinates and times of p¯s annihilating at rest in a H2 target at very low density ρ (ρ/ρ0<10−2, ρ0 being the STP density) gives the possibility of evaluating the behavior of the p¯ stopping power in H2 at low energies (below 120 keV). It is different from that of protons (the Barkas effect). Moreover, it is shown that a rise at low-energy values (≲1 keV) is needed to agree with experimental data.

Phys. Scripta

The ratio between the numbers of negative and positive leading pions in 20Ne reactions at 607 MeV/c can only be explained in terms of parton fragmentation.

Nucl.Instrum.Meth.A

The present article describes an apparatus used for the measurement of spin dependent observables at SATURNE II. Observables for np elastic and quasi-elastic scattering were measured between 0.31 and 1.1 GeV, those for pp elastic scattering between 1.94 and 2.24 GeV. Measurements of pn and pp observables with an unpolarized 6 LiD and 7 LiH targets around 2 GeV were also carried out. Fast electronics, on-line data acquisition, event selection and off-line analysis are presented.

Nucl.Phys.A

We present a total of 323 data points of the spin correlation parameter A oonn (np) in a large angular interval at eight energies between 0.8 and 1.1 GeV. The SATURNE II polarized beam of free neutrons obtained from the break-up of polarized deuterons was scattered on the polarized Saclay frozen-spin proton target. The present data are the first existing results above 0.8 GeV.

Nucl.Phys.A

We present a total of 273 independent data points of the analyzing powers A oono (nP) and A ooon (nP) in a large angular interval at four energies between 0.477 and 0.940 GeV. The SATURNE II polarized beam of free neutrons obtained from the break-up of polarized deuterons was scattered on the polarized Saclay frozen-spin proton target. Part of the data was obtained with a CH 2 target. A comparison of the two measured observables allows one to determine the polarization of the neutron beam. The present results provide an important contribution to any future theoretical or phenomenological analysis.

JACoW

The IHEP proton Accelerating and Storage Complex (UNK) includes in its first stage a 400 GeV conventional and a 3000 GeV superconducting ring placed in the same underground tunnel of 20.7 km circumference. The beam will be injected into UNK from the existing 70 GeV accelerator U-70. The experimental programme which is planned to start in 1995, will include 3000 GeV fixed target and 400-3000 GeV colliding beams physics. The size and complexity of the UNK dictate a distributed multiprocessor architecture of the control system. About 4000 of 8/16 bit controllers, directly attached to the UNK equipment will perform low level control and data acquisition tasks. The equipment controllers will be connected via the MIL-1553 field bus to VME based 32-bit front end computers. The TCP/IP network will interconnect front end computers in the UNK equipment buildings with UNIX workstations and servers in the Main Control Room. The report presents the general architecture and current status of the UNK control.