C.A. Wiedner

PERFORMANCE OF A QDDD SPECTROGRAPH.

Abstract A new type magnetic spectrograph for charged-particle nuclear-reaction studies has been put into operation in conjuction with the Heidelberg MP-Tandem Van de Graaff accelerator. The main elements of the spectrograph are a quadrupole magnet and three dipoles (deflecting magnets). It is therefore called the QDDD or Q3D spectrograph. The instrument has an acceptance solid angle of 13 msr, a range E max / E min = 1.21 and a resolving power of the order of p / Δp = 10 4 . Other features of the instrument include a multipole used for magnetic correction of kinematic broadening and other aberrations and an electrostatic deflector for separation of particles according to their specific mass m / q .

π+−16O elastic scattering from 80 to 340 MeV

Abstract We present preliminary results for π + − 16 O elastic scattering at 79, 114, 16, 240 and 343 MeV. Statistical uncertainties are about 5% for angular bins of 1.5°. The data are compared to a first-order momentum-space optical model calculation.

The SIN high resolution pion channel and spectrometer

The optical properties of the SIN high resolution pion channel and spectrometer are briefly reviewed. The operation of the whole system, including detectors and data acquisition is then described. Finally the tune-up method and the actual performances are given.

Spin alignment and polarisation in the (16O,15N) transfer reactions

The spin alignment of the15N32/* (6.33 MeV) state was measured in the88Sr(16O,15N)89Y reaction atEL=96 MeV using theγ-recoil method. Angular distributions of excited states in15N and89Y were measured with high accuracy. The analysis in terms of DWBA shows that the spin alignment is correctly described by the usual reaction models. The polarisation of the outgoing15N1/2(GS) and15N32/*(6.33 MeV) is discussed. It is shown that cross section differences for transitions to final states with different configurations are sensitive to a spin-orbit potential of15N. The strength and sign of the spin-orbit potential for15N is determined.

The multipole element of the Q3D spectrograph for correction of the kinematic broadening

Abstract An important property of the magnetic spectrographs of the Q3D type is the possibility to correct the kinematic broadening with a multipole magnet. The basic kinematic and magnetic formulae, the design and the performance of this special magnet are described. General limitations of the resolution due to kinematic effects are discussed and experimental results are given.

The mass and low-lying level structure of 17C

Abstract Spectra of 17 C ions from the 48 Ca( 18 O, 17 C) 49 Ti reaction at 102 MeV were recorded with a Q3D spectrograph. The lowest state observed, assumed to be the ground state of 17 C, has a mass excess of 21023±35 keV. An excited state of 17 C was also observed at an excitation energy of 292 ± 20 keV.

Study of the ground state doublet in57Fe

The56Fe(d,p)57Fe reaction has been studied at an incident energy of about 10 MeV. The ground state doublet of57Fe has been resolved using the Heidelberg Q 3 D magnetic spectrograph and the Minnesota split-pole spectrograph. The ratio of the spectroscopic strengths (2J+1)S for the transitions to the first excited state at 14.4 keV excitation energy (Jπ=3/2−) and the ground state (Jπ=1/2−) has been determined to be 5.80±0.5.This number is of special interest with respect to a possible deformation of the nucleus57Fe and in connection with the corresponding analogue resonances in57Co.

The mass of 15B via a three-proton stripping reaction

Abstract The isotope 15B was produced via the reaction 48Ca(18O, 15B)51V. The Q-value and mass excess were determined to be −21.76 ± 0.05 MeV and 28.96 ± 0.05 MeV, respectively. A search for the isotope 14Be was unsuccessful.

The d32 hole strength in the ground state of 44Ca

Abstract The proton stripping reaction 44 Ca (τ, d) 45 Sc (g.s., 12.4 keV) has been studied at E( 3 He ) = 24 MeV with the Heidelberg Q3D magnetic spectrograph. The strength of the transition to the ( d 3 2 ) hole state in 45 Sc was found to be (2 J f +1) C 2 S p =1.9.

Neutron and proton components of nuclear transitions in pion inelastic scattering on 26Mg

Abstract The elastic and inelastic scattering of 180 MeV positive and negative pions from 26 Mg has been measured. From these data the ratios of neutron and proton nuclear transition matrix elements have been determined for the first and second excited states. These ratios are compared with those obtained from electromagnetic transitions in mirror nuclei and with shell model predictions.