Elastic scattering of positive pions from 12C at 29 MeV

The elastic scattering cross section of positive pions at 29 MeV scattered from ¹²C has been measured at scattering angles between 15° and 150°. The cross section drops to a sharp minimum at about 40° and then rises to about 4 mb/sr at back angles.     

Quasi-free proton-scattering at 164 MeV

Inclusive proton spectra have been measured over the angular range 25° – 150° for 164 MeV protons on ²⁷Al, ⁵⁸Ni, ⁶²Ni and ²⁰⁸Pb. At 25° and 30° a peak attributable to quasi-free scattering, accounting for ≈20% of the total number of fast protons at these angles, is present. No quasi-free peak is evident in the spectra at larger angles. These results are in disagreement with previously published work at this energy but in line with results reported at other energies.     

The Ar(p, d)Ar reaction

The ³He spin analysing power of hydrogen (protons) has been measured at a c.m. energy of 20 MeV at 14 c.m. angles from 40° to 160°. The measurement of ³He target polarization was calibrated by measuring the ³He spin analysing power of ⁴He at an energy and angle where it was ?1.00. The proton-³He differential elastic scattering cross section is also reported at a c.m. energy of 20.0 MeV for 36 c.m. angles from 20° to 170°.     

Differential cross sections of neutral pion photoproduction from hydrogen in the energy region from 390 MeV to 975 MeV

The differential cross sections of the reaction γp→π⁰p have been measured at photon energies between 390 MeV and 975 MeV with an energy step of 20 or 25 MeV. The angular region covers 11 angles between 15° and 130° in the c.m.s. A combination of a magnetic spectrometer and photon detector was used for the measurement in the angular region from 50° to 130°. At forward angles of 15°, 35° and 50°, π⁰ mesons were detected using a π⁰ detector consisting of a pair of photon detectors. The data obtained with two different detection systems overlap at the angle of 50° and coincide with each other within the experimental error. The results are compared with those of phenomenological partial-wave analyses.     

Richtungskorrelation für Kernresonanzfluoreszenz und Lebensdauer des 412 keV-Niveaus von198Hg

Using the method of thermal Doppler-broadening of the emission line, the effective differential cross sections for nuclear resonance scattering for 412 keV photons by¹⁹⁸Hg has been measured for well defined scattering angles of 120° and 160°. The results indicate a partial mean lifetime for this energy level of τ_γ=(5·12±0·23)·10^?11 sec. This result differs appreciably from the values reported by other workers. Possible reasons for these discrepancies are discussed. The ratio of the differential cross sections for resonance scattering at angles of 120° and 160° is consistent with a 0-2-0 transition.     

7Li(α,n)10B differential cross-section measurements from threshold to Eα = 5.1 MeV

Differential cross sections for the ⁷Li(α, n)¹⁰B reaction have been measured at lab angles of 0°, 20°, 31°, 50°, 60°, 70°, 80°, 90°, 100° and 114° for α-particle energies between 4.385 and 5.1 MeV. A thick natural lithium target was bombarded with a 5.2 MeV, nanosecond-pulsed ⁴He⁺ beam and neutron velocity spectra at each angle were measured by time-of-flight techniques. These data have been converted to cross sections at 10 keV intervals in α-particle energy. Angular distributions have been fitted with a series of Legendre polynomials. Angle-integrated cross sections, the 0° excitation function, and angular distributions are compared to past measurements and R-matrix calculations.     

90° excitation functions for elastic scattering of 28Si+16O and 28Si+12C

The gross structures in the excitation functions for elastic scattering of ²⁸Si+¹⁶O and ²⁸Si+ ¹²C, measured at 90°, where only even partial waves contribute, are found to be anti-correlated with those at 180°. Excitation functions at both angles, including the enhanced gross structure at 180°, can be reproduced by calculations using a potential which attracts odd partial waves more than even partial waves.     

静态随机存储器单粒子效应的角度影响研究

利用兰州重离子加速器加速的高能离子研究了入射角度对IDT71256的单粒子翻转截面和多位翻转比例的影响.研究表明：在大角度掠射轰击下单粒子翻转截面的增大包括了多位翻转的贡献；离子在器件敏感层中沉积的能量及其横向分布是影响多位翻转的两个重要参数，IDT71256发生三位以上多位翻转的比例随着离子入射角度的增大而增加. 关键词： 静态存储器 单粒子翻转 多位翻转 沉积能量 横向分布     

Proton momentum spectra in high-energy reactions of 9Be and 12C with quasimonochromatic photons

Momentum spectra of protons emitted at three lab angles 23°, 55° and 130° in high-energy photoreactions of ⁹Be and ¹²C are studied by using tagged photons in the energy range between 360 and 600 MeV. At 23° and 55°, we observe a structure which may be ascribed to protons from quasifree production of a single pion and those from quasideuteron photodisintegration, while at 130°, the spectra are predominantly due to protons resulting from intranuclear multiple scattering. The results of an intranuclear cascade calculation are compared with the data.     

Elastic Scattering of α-Particles on Be9

The differential cross-section for the elastic scattering of He⁴ particles on Be⁹ has been studied in the bombarding energy range 1.4-2.5 MeV. The excitation functions for the elastically scattered α-particles from Be⁹ were measured at six angles 90°, 125°, 132°, 140°, 150° and 160° in the centre of mass system. A clear and pronounced resonance is observed in the measured cross-section at incident α-particle energy 1.93 MeV. Analysis of the data in terms of the single level approximation theory leads to the assignment Jπ = 5+/2 for the observed resonance. Reduced and partial widths for elastic scattering were determined.     

The parity violation A4 experiment at forward and backward angles

The A4 Collaboration at the MAMI accelerator in Mainz measures the parity-violating asymmetry in the cross-section of elastic scattering of longitudinally polarized electrons off unpolarized protons from which the contribution of strange sea quarks to the vector form factors of the proton can be derived. Measurements at forward angles 30^° ⩽ θ ⩽ 40^° and two different momentum transfers Q² of 0.23 (GeV/c)² and 0.11 (GeV/c)² have been performed in the past. Measurements at backward angles 140^° ⩽ θ ⩽ 150^° are underway for a separate determination of the strange electric and the strange magnetic form factor at Q ² = 0.23(GeV/c)² .     

Conventional and collision photon echo in ytterbium vapor

The polarization properties of the photon echo generated by two linearly polarized pulses of resonant radiation at the (6s6p)³ P ₁ ? (6s ²)¹ S ₀ transition of ¹⁷⁴Yb are investigated. A complicated polarization behavior of the photon echo versus an angle between the polarization vectors of the excitation pulses is revealed in a mixture of ytterbium vapor with inert gas. For the angles ranging from 0° to 75°, a conventional echo with its linear polarization coinciding with the second excitation pulse dominates and the echo amplitude decreases with an increasing angle. For the angles ranging from 75° to 89°, the photon echo is elliptically polarized. Finally, for an angle of 90°, the conventional echo disappears and the collision echo becomes linearly polarized along the first excitation pulse.     

高电荷态离子与Si(110)晶面碰撞的沟道效应研究

不同电荷态低速离子(Ar^q+,Pb^q+)轰击Si(110)晶面,测量不同入射角情况下的次级粒子的产额. 通过比较溅射产额与入射角的关系,证实沟道效应的存在. 高电荷态离子与Si相互作用产生的沟道效应说明溅射产额主要是由动能碰撞引起的. 在小角入射条件下,高电荷态离子能够增大溅射产额. 当高电荷态离子以40°—50°入射时,存在势能越高溅射产额越大的势能效应. 关键词： 高电荷态离子 溅射 沟道效应     

Elastic backward scattering of positive pions from 12C at 23, 29 and 35 MeV

The elastic scattering of positively charged pions at 23, 29 and 35 MeV scattering from ¹²C has been measured at 161°, 168° and 176° scattering angles. The new measurements give a backward descending behaviour to the existing angular distribution at 30 MeV. The complete angular distribution is compared to a calculation based upon the only Ericson-Ericson-Lorentz-Lorenz effect and to the theoretical models of Landau and Thomas and of Stricker et al. for low-energy pion-nucleus scattering.     

Investigation of the lateral spread of erbium ions implanted in silicon crystal

The erbium ions at energy of 400 keV and dose of 5×10 15 ions/cm 2 were implanted into silicon single crystals at room temperature at the angles of 0,45 and 60.The lateral spread of 400 keV erbium ions implanted in silicon sample was measured by the Rutherford backscattering technique.The results show that the measured values were in good agreement with those obtained from the prediction of TRIM’98 (Transport of Ions in Matter) and SRIM2006 (Stopping and Range of Ions in Matter) codes.     

Investigation of the inclusive spectra of secondary protons and pions of low kinetic energies and of their wide pair correlations in π − A interactions at 43 GeV/c

The inclusive invariant cross sections for protons produced at angles of θ=90° and 60° and for positively and negatively charged pions produced at an angle of θ=90° are presented for π ^?Be, π ^?Al, and π ^?Cu interactions induced by 43-GeV/c incident π ^? mesons. The shape of the inclusive spectra of secondary hadrons, the A dependence of their cross sections, and the correlation functions for pairs of likely charged secondary hadrons at large angles of their divergence are studied. The kinematical region explored in the present article corresponded to kinetic energies of T≈0.16–0.70 GeV and T≈0.20–0.76 GeV for secondary protons and secondary pions, respectively. The angles of divergence of hadrons forming a pair, ψ, satisfied the condition cos ψ相似文献   

Neutron dose distribution from 12C induced reactions on Ti and Ag using proton recoil scintillator

We measured the double differential neutron yield at 0°, 30°, 60° and 90° from ¹²C⁵⁺ induced reactions on thick targets of Ti and Ag at 12 MeV/amu at the Cyclotron at National Institute of Radiological Sciences, Inage, Japan, with 5″ × 5″ proton recoil scintillation detectors BC-501. The measured neutron spectra were unfolded using pulse height unfolding algorithm and energy and angular distribution obtained. Energy distribution of neutron ambient dose equivalent, H*(10) and absorbed dose, D at different angles was determined from double differential neutron spectra using ICRP recommended fluence to dose conversion coefficients.     

Reducing bias in DREAM flip angle mapping in human brain at 7T by multiple preparation flip angles

DREAM (Dual Refocusing Echo Acquisition Mode) is an ultra-fast multi-slice B₁⁺-mapping technique based on the single-shot STEAM sequence. To study systematic errors at high actual flip angles (FA) and low SNR, DREAM B₁⁺ maps at 3.75×3.75×3.50 mm³ resolution were acquired at 7T in phantoms and human brain in vivo with nominal FAs between 20° and 90° for the two STEAM preparation pulses. Predicted B₁⁺ estimates were underestimated at actual FAs above 50° while noise was prominent below 20°. With a reliable interval of the actual FA between 20° and 50° identified, a B₁⁺ range of 33% - 200% of nominal FA is covered by varying the nominal preparation angle through 25°, 40°, and 60°. Individual B₁⁺ maps are thresholded according to the identified interval and combined into a single map. We demonstrate the benefit of the combined low-noise, low-bias B₁⁺ maps for dual flip angle T₁-mapping.     

Production rates of excited fragment isotopes from the36Ar+Ag reaction at 35 MeV/nucleon

Previous studies showed that the binding energy plays a systematic and important role in the production of ground-state fragments in intermediate energy, heavy ion reactions. The production rates were measured as a function of fragment kinetic energy at angles of 15°, 30°, 45° and 60° for excited fragments of⁷Li,⁸Li,¹¹Be and¹²B. Using a thermal model the total production of neutron unbound excited states was determined, and it was found that their production rates correspond to the previous systematic behaviour using the binding energies corrected by the excitation energies.