Overview

The High Transmission Beam Line (HTBL) and the Spectrometer Section (SPS) constitute the two segments of the High Rigidity Spectrometer (HRS). HTBL and SPS are being delivered as separate subprojects. Prior to completion of the SPS, the HTBL will be used for experiments in the High rigidity Rare Isotope Beams at Zero Degrees (HiRIBZ) mode.

In the HiRIBZ mode, beams can be delivered to a target station place in the middle of the HTBL and surrounded by detection systems with a modest footprint, such as the g-ray detection arrays SeGA and CAESAR, the low-energy neutron detector array LENDA, or charged-particle detection near the target. A focal plane detector system is available at the end of the HTBL for identification and momentum determination of particles produced in reactions at the HiRIBZ target station. The focal plane detector system will have detectors for time-of-flight measurements (thin plastic scintillator), tracking detectors for momentum and angle measurements (PPACs), energy loss (silicon detector) and total kinetic energy measurements (scintillator crystals). Isotopes with mass number of up to about 132 and atomic number of about 50 can be separated in the focal plane. Intermediate tracking stations are also available in the HTBL.

Alternatively, beams can be delivered to the end of the HTBL, and detector systems can be employed as end stations in experiments with fast rare-isotope beams. 

HiRIBZ will be able to transport beams with a rigidity of up to 8 Tm with high transmission. The angular acceptance is 3.6 msr and the momentum acceptance is ±2.0%. Different ion-optical transport schemes can be used, including achromatic and dispersion-matched ion-optical transport modes. 

Grant acknowledgement: HRS is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under award number DE-SC0024098.