Radioactive Ion Beam (⁷Be)

HIRA, operated in mass achromatic mode with important add-ons, has been shown to deliver light radioactive ion beam of excellent purity and moderate intensity using (p,n), (d,n) type of reactions in inverse kinematics and in-flight technique. Primary beams of stable, light nuclei from the 15 UD Pelletron accelerator are used on hydrogenous target and the radioactive secondary particles are separated in-flight and re-focused at a secondary target position using the existing recoil mass spectrometer, HIRA, operated in a new ion-optical mode. To satisfy the ion-optical requirement of a well defined beam spot-size, polyethylene foil targets mounted on a rotary/linear motion device are used. In the new optics, there is a momentum dispersed focal plane at the center of the magnetic dipole. A slit system with in-vacuum transfer option is installed at this focal plane, to selectively transmit secondary radioactive particles of specific energy window to the final focal plane. The large energy and momentum dispersion achieved till the centre of MD helps in high selectivity of the secondary particles. The second half of HIRA cancels the energy and momentum dispersion resulting in excellent secondary beam quality at the focal plane. The four quadrupoles help in achieving good focus of selected particles at MD centre and at the focal plane.

We have optimized the facility for production of ⁷Be beam using the p(⁷Li,⁷Be)n reaction, with the following features:

The focal plane chamber of HIRA acts as the scattering chamber for reactions with secondary beam. It houses "triple axis movement" collimator as well as the detector set-up. Since its commissioning, the facility has been used to carry out a number of low energy nuclear reactions using ⁷Be secondary beam.