Abstract

The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, CERN, uses laser radiation to stepwise excite and ionize an atomic beam for the purpose of ultra-sensitive detection of rare isotopes, and hyperfine-structure measurements. The technique also offers the ability to purify an ion beam that is heavily contaminated with radioactive isobars, including the ground state of an isotope from its isomer, allowing decay spectroscopy on nuclear isomeric states to be performed. The isomeric ion beam is selected by resonantly exciting one of its hyperfine structure levels, and subsequently ionizing it. This selectively ionized beam is deflected to a decay spectroscopy station (DSS). This consists of a rotating wheel implantation system for alpha- and beta-decay spectroscopy, and up to three germanium detectors around the implantation site for gamma-ray detection. Resonance ionization spectroscopy and the new technique of laser assisted nuclear decay spectroscopy have recently been performed at the CRIS beam line on the neutron-deficient francium isotopes. Here an overview of the two techniques will be presented, alongside a description of the CRIS beam line and DSS. © Owned by the authors, published by EDP Sciences, 2013.

Highlights

  • The Collinear Resonance Ionization Spectroscopy (CRIS) experiment [1] at ISOLDE, CERN, utilities the selectivity of resonance ionization to perform decay spectroscopy on pure nuclear isomeric states [2]

  • With the technique of laser assisted nuclear decay spectroscopy, alpha- and gamma-decay measurements can be performed on each isomeric beam separately

  • The collinear geometry of the setup gives a reduction in the thermal Doppler broadening by a factor of 103, improving resolution compared to in-source spectroscopy

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Summary

Introduction

The Collinear Resonance Ionization Spectroscopy (CRIS) experiment [1] at ISOLDE, CERN, utilities the selectivity of resonance ionization to perform decay spectroscopy on pure nuclear isomeric states [2]. The novel technique of laser assisted nuclear decay spectroscopy in a collinear geometry combines hyperfine structure measurements with radioactive-decay measurements, providing additional information on the isotope, or isomer, under investigation. With the technique of laser assisted nuclear decay spectroscopy, alpha- and gamma-decay measurements can be performed on each isomeric beam separately. By utilising the collinear resonance ionization method as a purification technique, isomeric beams can be studied, answering questions on the presence, lifetime and decay mechanism of each state.

Collinear resonance ionization spectroscopy
The CRIS beam line
The decay spectroscopy station
Experimental efficiency
Hyperfine measurements with CRIS
Conclusions and Outlook
Laser assisted nuclear decay spectroscopy
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