Study of the reaction π− p→η′η′n

The reaction π^? p→η′η′n has been studied atp _π=37 GeV/c. Total of 14 events of this reaction have been selected. It has been shown that in the effective mass spectrum of the η′η′ system the events are concentrated mainly near the reaction threshold, which might be caused by the decayX(1910)→η′η′. The reaction cross-section has been evaluated: σ(π^? p→η′η′n)=110±40 nb.     

Effect of the crystal structure of a deuterated target on the yield of neutrons in the dd reaction at ultralow energies

The energy dependence of the neutron yield in the d(d, n)₃ He reaction proceeding in a textured titanium deuteride target with the preferred orientation of microcrystals in the [100] direction has been studied. Measurements have been performed for the energy range of incident deuterons of 7–12 keV in the laboratory system. It has been shown that the energy dependence of the enhancement factor of the reaction is described not only by the screening potential but also by the simple inclusion of channeling effects.     

Low-energy cross sections for11B(p, 3α)

The¹¹B(p, 3α) reaction has been investigated in the energy range fromE _c.m.=22 to 1100 keV with the use of either a proton beam and a¹¹B solid target or with the use of a¹¹B heavy ion beam incident on a hydrogen jet gas target. The reaction mechanisms have been studied via kinematically complete coincidence measurements showing that the reaction proceeds predominantly by a sequential decay via⁸Be. The measurement of absolute cross sections,α-angular distributions and excitation functions is reported. The astrophysicalS(E) factor has been described by means of an empirical fit to the data, leading to a zero-energy intercept ofS(0)=197±12 MeVb. Conclusions drawn on the use of this reaction as an advanced fuel in fusion reactors remain essentially unchanged by the present data.     

Seach for QFS Anomaly in pd Breakup Reaction Below E p = 19 MeV

Space Star anomaly in Nd breakup reaction below 20 MeV is well-known. Also, Quasi-Free Scattering (QFS) anomaly in Nd breakup reaction below 40 MeV has been reported from several experiments. Origin(s) of QFS anomaly has not been known, similarly to origin(s) of SS anomaly. We have been making a systematic measurement on pp-QFS cross section, previously at E _p = 9.5 MeV and 13 MeV and recently at 7.5 and 19 MeV. We used an unpolarized p-beam to correctly measure only cross section. Our data agreed well with pd calculation by A. Deltuva. So far, no pp-QFS anomaly has been found in our experiments.     

Electroproduction of η-meson at the S11 (1535) resonance

The reaction e^? + p → e^? + p + η has been studied in the region of the S₁₁ (1535)-resonance by detecting the recoil proton in coincidence with the scattered electron. The reaction has been observed at three four-momentum transfers of the virtual photon: q² = 0.2, 0.28 and 0.4 (GeV/c). First results of the differential cross section measurements are given and compared with quark model calculations.     

Spectroscopy of highly excited states in29Si

Particleγ-ray coincidences have been measured in the²⁸Si (d,pγ) reaction at 6.5 and 7 MeV bombarding energy, in the²⁶Mg (α,nγ) reaction at 12, 14 and 15 MeV, and in the²⁷A1 (τ,pγ) reaction at 9 MeV. Theγ-decay has been observed for all bound states of²⁹Si and for 56 unbound states up to 12,960 KeV excitation energy. Particleγ-ray angular correlations were measured in the²⁸Si (d,pγ) reaction at 6.5 MeV and in the²⁶Mg (α,nγ) reaction at 12 MeV. Spin (-parity) assignments or restrictions were obtained for nearly all bound states and some high-spin states above the binding energy. The assignment of mirror levels in²⁹Si and²⁹P has been extended to 8.2 MeV excitation energy. The excitation energies of 41 positive-parity states are reproduced by shell model calculations. The possible existence of aK ^π=5/2⁺ band with prolate deformation is discussed.     

Isotope effects in the kinetics of simultaneous H and D thermal desorption from Pd

The kinetics of simultaneous hydrogen and deuterium thermal desorption from PdH_xD_y has been investigated. A novel experimental approach for the study of the transition state (TS) characteristics of the surface recombination reaction is proposed based on the analysis of the H and D partitioning into H₂, HD and D₂ molecules. It has been found that the hydrogen molecular isotopes distribution is determined by the energy differences of the corresponding TS of the atom-atom recombination reactions. On the other hand, the mechanisms and activation energies of the desorption process have been obtained. At 420 K, the desorption reaction changes from a surface recombination limiting mechanism during desorption from β-PdH_xD_y to a reaction limited by the rate of β to α phase transformation during the two phase coexistence. Surface recombination reaction becomes again rate limiting above 480 K, due to a change in the catalytic properties of the Pd surface. TS energies obtained from the kinetic analysis of the thermal desorption spectra are in good accordance with those obtained from the analysis of the H₂, HD and D₂ distributions. Anomalous TS energies have been observed for the H-D recombination reaction, which may be related to the heteronuclear character of this molecule.     

Energy levels,decay scheme, γ-ray branching ratios and lifetimes in 55Fe from the 55Mn(p,nγ)55Fe reaction

The reaction ⁵⁵Mn(p, nγ)⁵⁵Fe has been studied at E_p = 4.0 and 6.0 MeV using a pulsed beam. From the experiments at 6.0 MeV, the energy levels of ⁵⁵Fe up to an excitation of 3810 keV, their decay scheme and the γ-ray branching ratios have been determined. Levels have been identified for the first time in the (p, nγ) reaction. The results have been compared with those available from the literature. From the 4.0 MeV experiment, the mean lifetime of the 1408 keV level has been determined to be 142.7 ± 6.6 ps by direct timing techniques.     

Reaction rate of 24Mg(p,γ)25Al

The proton-capture reaction on ²⁴Mg has been investigated in the bombarding energy range of E_p=0.2–1.7 MeV. Resonance properties (strengths, branching ratios and lifetimes) of low-energy resonances have been measured. From the experimental results, accurate proton partial widths, γ-ray partial widths and total widths (Γ_p, Γ_γ, and Γ) have been deduced. The present experimental information establishes the ²⁴Mg+p reaction rates over the temperature range T=0.02–2.0 GK with statistical uncertainties of 5% to 21%. Our recommended reaction rates deviate from previous estimates by 18% to 45%. Based on our results, we can rule out the recent suggestion that the total width of the E_R=223 keV resonance has a significant influence on the reaction rates. We also discuss several effects that might give rise to systematic uncertainties in the reaction rates. The astrophysical implications for hydrogen burning of ²⁴Mg at low stellar temperatures are presented.     

Measurement and simulation of the cross sections for nuclide production in natW and 181Ta targets irradiated with 0.04- to 2.6-GeV protons

The cross sections for nuclide production in thin ^natWand ¹⁸¹Ta targets irradiated by 0.04–2.6-GeV protons have been measured by direct γ spectrometry using two γ spectrometers with the resolutions of 1.8 and 1.7 keV in the ⁶⁰Co 1332-keV γ line. As a result, 1895 yields of radioactive residual product nuclei have been obtained. The ²⁷Al(p, x)²²Na reaction has been used as a monitor reaction. The experimental data have been compared with the MCNPX (BERTINI, ISABEL), CEM03.02, INCL4.2, INCL4.5, PHITS, and CASCADE07 calculations.     

Evidence for large angular momentum window associated with incomplete fusion reactions

Mean values and variances of the angular momentum window of incomplete fusion reactions induced by¹⁶O on^116–124Sn targets at 90, 100 and 125 MeV have been measured. Theγ multiplicity technique has been used to extract these quantities for each reaction channel identified by discreteγ lines. Incomplete fusion seems to appear in about the same angular momentum window than complete fusion. This is confirmed by the observation of α 2p4n and 2α4n channels appearing at low angular momentum in the 125 MeV reaction.     

Measurement of ΔσL in pp scattering between 200 and 583 MeV

The main structure around m = 2.15 GeV first observed by the Argonne group in the spin-dependent total cross section Δσ_L is confirmed in the energy range available at SIN. A simultaneous study of the scattered particles at small angles has been carried out with success and gave the spin-correlation parameter A_00kk for the pp elastic scattering and for the reaction pp → π⁺d. The contribution of the 3-body reactions to this spin-dependent total cross section has been deduced and found to be lower than the contribution of the π⁺d reaction even at 583 MeV.     

Measurement and simulation of the cross sections for nuclide production in 93Nb and natNi targets irradiated with 0.04- to 2.6-GeV protons

The cross sections for nuclide production in thin ⁹³Nb and ^natNi targets irradiated by 0.04- to 2.6-GeV protons have been measured by direct γ spectrometry using two γ spectrometers with the resolutions of 1.8 and 1.7 keV in the ⁶⁰Co 1332-keV γ line. As a result, 1112 yields of radioactive residual nuclei have been obtained. The ²⁷Al(p, x)²²Na reaction has been used as a monitor reaction. The experimental data have been compared with the MCNPX (BERTINI, ISABEL), CEM03.02, INCL4.2, INCL4.5, PHITS, and CASCADE07 calculations.     

Detection of free radicals formation in haemolymph of insects by EPR spectroscopy

The generation of reactive oxygen species during oxidation of DOPA (3-(3,4-dihydroxyphenyl-DL-alanine) in haemolymph of insects has been studied by electron paramagnetic resonance with spin traps 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide and 1-hydroxy-3-carboxy-pyrrolidine. The data support the formation of DOPA-derived highly reactive intermediates during melanization in haemolymph of insects. The formation of superoxide has not been detected apparently due to reaction of DOPA with superoxide. The rate constant of the latter reaction was estimated ask≈5·10⁵ M^?1.c^?1. The formation of DOPA-semiquinone in haemolymph has been measured using spin stabilization ofo-semiquinones by Mg²⁺. The comparative studies in haemolymph of intact insects and insects infected by fungal infection suggest an important role of DOPA-semiquinone production in the immune status of insects.     

Ultrasound-promoted solvent-free aza-Michael addition of p-toluenesulfonamide to fumaric esters by potassium carbonate: Synthesis of p-toluenesulfonamide derivatives

An efficient, mild, inexpensive and eco-friendly protocol for the synthesis of p-toluenesulfonamide derivatives by aza-Michael addition reaction of p-toluenesulfonamide to fumaric esters using potassium carbonate under ultrasound irradiation was developed. This method is simple, convenient and the desired compounds are produced in good to excellent yield. The bulkiness of alkoxy group (–OR) of fumaric esters did not affect significantly on the yields and reaction times. This reaction worked well on linear and nonlinear alkyl fumarates. The reaction, surprisingly, was not successful on methyl fumarate. In this case methyl fumarate has been hydrolyzed to fumaric acid under reaction conditions.     

Thermodynamic and kinetic properties of Ho1−xTixCo2-hydrogen system

The hydrogen absorption behavior of Laves phase Ho_1−xTi_xCo₂ (x=0.1-0.6) alloys has been investigated by pressure-concentration (PC) isotherms and cyclic-, temperature- and pressure-dependent absorption kinetics. The PC isotherms and kinetics of hydrogen absorption have been studied in the pressure range 0.01-1 bar and temperature range 50-200 °C using Sievert's-type apparatus. The drastic changes in the induction period and particle size during the activation process have been discussed based on the kinetics of repeated hydrogenation cycles and scanning electron microscopy (SEM) images of the hydrides at different hydriding cycles, respectively. The experimental results of kinetic curves are interpreted using the Johnson-Mehl-Avrami (JMA) model, and the reaction order and reaction rate have been determined. The α-, (α+β)- and β-phase regions in Ho_1−xTi_xCo₂-H have been identified from the different slope regions of the first-order-type kinetic plots. The dependence of the reaction rate parameter on hydriding pressure and temperature in the (α+β)-phase region has been discussed.     

Voltage calibration of low-energy accelerators

The¹²C(p, γ)¹³N reaction has been used as a method to determine the absolute proton beam energy in the region ofE _p =150–350 keV with a precision of the order of 0.4 keV. The method makes use of the resulting captureγ-ray transition, whose intensity varies smoothly with beam energy and whose varying energy can be determined to high accuracy by comparison with precisely known energies ofγ-rays from radioactive sources. The energy calibration atE _p =80–150 keV has been carried out with the use of the nonresonant capture reaction D(p, γ)³He. The results have been applied to determine the absolute energies of proton-induced resonances on several light target nuclei.     

The reaction 23Na(n, γ)24Na studied with unpolarized and polarized thermal neutrons

The γ-radiation produced by thermal neutron capture in a natural Na sample has been investigated. Of the 158 γ-rays ascribed to the ²³Na(n, γ)²⁴Na reaction, 143 have been placed in a ²⁴Na decay scheme accounting for 100(2) % of the total primary strength. The reaction Q-value amounts to 6959.42 ± 0.08 keV. The data resulted in spin assignments for four and spin restrictions for six levels.The circular polarization of 14 γ-rays from the capture of polarized neutrons has been measured. The contribution of the J^π = 2⁺ channel in thermal capture was determined to be below 5 %.     

Investigation of the level structure of17O

The reactions¹²C(⁷Li,d) and¹³C(⁷Li,t) have been studied atE _C.M.=13.3. MeV. Spin assignments have been extracted from the integrated cross sections of the first reaction. The latter reaction has been analysed in terms of a modified-DWBA code.