Instruments
Status: Operational
Location: S3 Vault
Contact person: Jorge Pereira
Overview
The S800 Spectrograph is equipped with sensitive detectors that measure the positions and angles of particles deflected by the magnetic fields. Sophisticated software is then used to deduce the characteristics of the particles before and after the reaction. Various types of experiments are performed using this technique, sometimes in combination with other types of detectors located around the target to get a more complete picture of each reaction. For example, strange modes of vibration of nuclei can be studied, as well as exchange of nucleons (protons or neutrons) during the split moment of a nuclear reaction between an accelerated nucleus and a target nucleus.
Technical detail
The S800 Spectrograph combines both high resolution and high acceptance in a single device and is specially designed for reaction studies with radioactive beams. Its large acceptances both in solid angle (20 millisteradians) and momentum (5 percent) are well adapted to the large emittances of secondary beams produced by projectile fragmentation. The high resolution is achieved via an analytical reconstruction method in which aberrations are calculated a priori from the magnetic field maps and used directly to correct the raw data. The spectrograph is installed vertically on a carriage that can rotate from 0 to 60 degrees. Its maximum rigidity is limited to 4 Teslameter (Tm). The S800 is preceded by an analysis line that allows for different optical modes of operations, either focusing or dispersion matched.
Funding acknowledgement: The S800 construction was initiated under the NSCL Phase II construction project (NSF PHY-8215585) and completed under the NSCL Cooperative Operative Agreement (NSF PHY-9214992).
