Crystal-Barrel@ELSA experiments

For results of the CB-ELSA experiment, please, refer to the publications section.

 

More information on future projects and upgrades can be found here.

CB-ELSA/TAPS (TR 16) (measuring 2005-...)

 

 

CB-ELSA TR16 experimental setup.

The new beam times are currently being planned. The major changes for the new beam times include:

• Availability of linearly and circularly polarised photons after moving to the new experimental area
• The three rings of crystals in forward direction are combined in a new detector with fast triggering capabilities and charged particle vetos in front of the crystals.
• Mini-TAPS and MOMO for the very forward angles
• Polarised targed (butanol)
• New tagging system

Forward detector plug and Mini-TAPS

 

CBELSA/TAPS (measuring 2001-2003)

 

 

For CBELSA/TAPS, the forward three rings of the Crystal Barrel were removed and TAPS was positioned in forward direction.

• Availability of polarised beam photons using bremsstrahlung off a diamond crystal
• New tagging system with better resolution and high rate stability: Scintillating fibres were implemented to replace upper MPWC (higher rates, better resolution).
• Fast forward triggering capability and better resolution using TAPS, greater coverage of solid angle than with the Crystal Barrel alone
• Triggering:  TAPS, inner detector, FACE
• Targets: LH₂, LD₂, C, Ca, Nb, Pb

For results of the CBELSA/TAPS experiment, please, refer to the publications section.

CB-ELSA (measuring 2000-2001)

 

 

The characteristics of the experiment were:

• Incident electron beam energies of up to 3.2 GeV
• Photons produced by bremsstrahlung of amorphous copper radiator
• Energy determination of scattered electrons in dipole spectrometer. The tagging system consisted of a large magnet and the tagging hodoscope (14 scintillators for timing, 352 wires in two proportional chambers for spatial resolution).
• Tagged photon energies between 25 and 95% of the incident electron energy
• Liquid hydrogen target
• Inner scintillating fibre detector for charged particle identification consisting of 513 fibres arranged in three layers with different orientations with respect to the beam: parallel, +25°, -25° (helix).
• Time-of-flight walls in forward direction (θ < 12°)
• Photon detector for flux determination (lead mineral oil Cherenkov)
• Triggering: Hit in tagging system, multiplicity in final state >2 (3), proton in inner detector or TOF

The CB-ELSA experiment used the Crystal Barrel in its original arrangement.