The WITCH experiment: Acquiring the first recoil ion spectrum

TL;DR

The WITCH experiment measures recoil ion spectra in nuclear beta-decay to test for potential exotic interactions beyond the standard model, providing initial data and technical insights from CERN's ISOLDE facility.

Contribution

This work presents the first recoil ion spectrum measurement in beta-decay using a novel Penning trap and retardation spectrometer setup at CERN.

Findings

First recoil ion energy spectrum obtained

Experimental setup demonstrated to be fully operational

Initial data acquired during 2006 campaign

Abstract

The standard model of the electroweak interaction describes beta-decay in the well-known V-A form. Nevertheless, the most general Hamiltonian of a beta-decay includes also other possible interaction types, e.g. scalar (S) and tensor (T) contributions, which are not fully ruled out yet experimentally. The WITCH experiment aims to study a possible admixture of these exotic interaction types in nuclear beta-decay by a precise measurement of the shape of the recoil ion energy spectrum. The experimental set-up couples a double Penning trap system and a retardation spectrometer. The set-up is installed in ISOLDE/CERN and was recently shown to be fully operational. The current status of the experiment is presented together with the data acquired during the 2006 campaign, showing the first recoil ion energy spectrum obtained. The data taking procedure and corresponding data acquisition system are described in more detail. Several further technical improvements are briefly reviewed.