Lifetime measurement of excited low-spin states via the (p,p′γ) reaction

Abstract

In this article a method for lifetime measurements in the sub-picosecond regime via the Doppler-shift attenuation method (DSAM) following the inelastic proton scattering reaction is presented. In a pioneering experiment we extracted the lifetimes of 30 excited low-spin states of 96 Ru, taking advantage of the coincident detection of scattered protons and de-exciting γ-rays as well as the large number of particle and γ-ray detectors provided by the SONIC@HORUS setup at the University of Cologne. The large amount of new experimental data shows that this technique is suited for the measurement of lifetimes of excited low-spin states, especially for isotopes with a low isotopic abundance, where (n, n γ) or -in case of investigating dipole excitations -(γ, γ ) experiments are not feasible due to the lack of sufficient isotopically enriched target material.

Collective excitations ofRu96by means of(p,p′γ)experiments

“…For those states where a previously measured lifetime value was available in literature our new value is in remarkably good agreement [39]. For several states it was possible to analyze more than one depopulating transition.…”

“…As discussed in Refs. [37][38][39], the coincident detection of scattered protons and de-exciting γ-rays has several advantages. In particular, the lifetimes extracted from γ-ray spectra that were gated on the excitation energy of the level of interest are not affected by feeding contributions.…”

“…(1). Detailed information on the method of lifetime determination via the (p,p γ) reaction and the pγ-coincidence technique have been published in a dedicated article [39].…”

Decay of quadrupole-octupole1−states inCa40andCe140Derya1, Tsoneva2, Aumann3 et al. 2016Phys. Rev. CSelf Cite12120View full textAdd to dashboardCite

“…The evaluated data serve as a systematic basis for the discussion of two-phonon E1 excitations like, e.g., in the Sn isotopes [7,47], for N = 82 isotones [48] and in the compilation of Andrejtscheff et al [49] for A = 48 − 148 nuclei. An alternative way to determine B(E1) strengths in particular for states of rare isotopes, for which NRF measurements are difficult, are lifetime measurements using the Doppler-shift attenuation method (DSAM) in particle-γ coincidence measurements [50]. Since several years, the DSAM technique is applied in inelastic neutron-scattering at the University of Kentucky [51,52].…”

Combining γ-ray and particle spectroscopy with SONIC@HORUS

“…The particle-γ angular correlations measured with the setup are in good agreement with theoretical calculations; details will be discussed in an upcoming publication. Additionally, the high granularity can be used to determine γ-ray energy centroid shifts and deduce lifetimes with the DSA method [7] or to correct the Doppler-shift as explained in Section 5.2. SONIC (Silicon Identification Chamber) is a new array of up to twelve silicon particle detectors.…”