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WITCH (standing for "Weak Interaction Trap for Charged particles"), or experiment IS433, is a double Penning trap experiment to measure the recoil energy of decaying nuclei. A spectrometer in combination with a position-sensitive microchannel plate detector is used to count ions (with the MCP) while scanning their energy (using the spectrometer). The experiment is located at the ISOLDE Radioactive Ion Beam Facility in CERN. The beam from ISOLDE is bunched by REXTRAP after which it is transferred to the WITCH set-up.
Working principle

The ion bunch from REXTRAP is slowed in a pulsed drift cavity in the vertical beamline. After this the bunch is injected into the 9 T magnetic field. Here the ion cloud is trapped in the first Penning trap (for cooling). Its purpose is to cool down the ions with buffer gas. In this trap, it is possible to apply different excitation modes (dipolar, quadrupolar and octopolar). The ions are then transferred to the second Penning trap (in which decays are studied).

When an ion decays, it can escape the decay trap into the spectrometer. The spectrometer consists out of a set of electrodes to create an electrical potential barrier. If the decayed ion's energy is high enough, it will be able to overcome this barrier to be detected at the top of the setup.
Physics goal

The first goal of the experiment is to measure the so-called beta-neutrino correlation. This is indirectly done by measuring the shape of the spectrum of the recoiling ions. This beta-neutrino correlation can provide, if measured precisely, information about fundamental weak interaction properties. According to the Standard Model the weak interaction has a Vector–Axial vector structure. But there are other mathematical possibilities which have not been detected in nature yet. The WITCH experiment will search for scalar currents in the first place. But it is also possible to look for tensor currents.

Other physics goals are the search for heavy neutrinos, measuring Fermi/Gamov-Teller mixing ratios, measuring electron capture probabilities, etc.
References

WITCH Homepage

vte

Neutrino detectors, experiments, and facilities
Discoveries

Cowan–Reines ( νe ) Lederman–Schwartz–Steinberger ( νμ) DONUT ( ντ) Neutrino oscillation SN 1987 neutrino burst

Operating
(divided by primary neutrino source)
Astronomical

ANITA ANTARES ASD BDUNT Borexino BUST HALO IceCube LVD NEVOD SAGE Super-Kamiokande SNEWS

Reactor

Daya Bay Double Chooz KamLAND RENO STEREO

Accelerator

ANNIE ICARUS (Fermilab) MicroBooNE MINERνA MiniBooNE NA61/SHINE NOνA NuMI T2K

0νββ

AMoRE COBRA CUORE EXO GERDA KamLAND-Zen MAJORANA NEXT PandaX SNO+ XMASS

Other

KATRIN WITCH

Construction

ARA ARIANNA Baikal-GVD BEST DUNE Hyper-Kamiokande JUNO KM3NeT SuperNEMO FASERν

Retired

AMANDA CDHS Chooz CNGS Cuoricino DONUT ERPM GALLEX Gargamelle GNO Heidelberg-Moscow Homestake ICARUS IGEX IMB K2K Kamiokande KARMEN KGF LSND MACRO MINOS MINOS+ NARC NEMO OPERA RICE SciBooNE SNO Soudan 2 Utah

Proposed

CUPID GRAND INO LAGUNA LEGEND LENA Neutrino Factory nEXO Nucifer SBND UNO JEM-EUSO WATCHMAN

Cancelled

DUMAND Project Long Baseline Neutrino Experiment NEMO Project NESTOR Project SOX BOREX

See also

BNO (Baksan or Baxan Neutrino Observatory) Kamioka Observatory LNGS SNOLAB List of neutrino experiments

vte

European Organization for Nuclear Research (CERN)
Large Hadron Collider (LHC)

List of LHC experiments ALICE ATLAS CMS LHCb LHCf MoEDAL TOTEM FASER

Large Electron–Positron Collider (LEP)

List of LEP experiments ALEPH DELPHI OPAL L3

Super Proton Synchrotron (SPS)

List of SPS experiments AWAKE CNGS NA48 NA49 NA58/COMPASS NA60 NA61/SHINE NA62 UA1 UA2 BIBC LEBC HOLEBC

Proton Synchrotron (PS)

PSB LEIR BEBC PS215/CLOUD Gargamelle 2 m Bubble Chamber 30 cm Bubble Chamber 81 cm Saclay Bubble Chamber

Linear accelerators

AWAKE CTF3 CLEAR LINAC 1 LINAC 2 LINAC 3 LINAC 4

Other accelerators

AA (part of AAC) AC (part of AAC) AD ISOLDE
ISOLTRAP WITCH ISR LEAR
PS210 LEIR LPI (LIL and EPA) n-TOF SC SppS

Non-accelerator experiments

CAST

Future projects

High Luminosity Large Hadron Collider Compact Linear Collider Future Circular Collider

Related articles

LHC@home Safety of high-energy particle collision experiments CERN Courier CERN openlab Worldwide LHC Computing Grid Microcosm exhibition Streets in CERN The Globe of Science and Innovation Particle Fever (2013 documentary)

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