Speaker
Dr
Benjamin Kay
(Argonne National Laboratory)
Description
The new helical-orbit spectrometer, HELIOS [1,2], at Argonne National Laboratory (ANL) provides a way of studying transfer reactions in inverse kinematics that circumvents the problems traditionally associated with this reaction mode: low resolution brought on by the rapidly changing laboratory energy with angle, and a kinematic compression at forward c.m. angles. This is achieved by transporting outgoing ions in the strong, homogeneous magnetic field of a solenoid, where the ions execute helical orbits before returning to the magnetic axis. The field disperses ions according to their energy, angle of emission, and charge-to-mass ratio giving rise to the particle’s cyclotron period which provides particle identification. Along the axis, surrounding it, is an array of position-sensitive Si detectors used to measure energy, position, and time of flight. This detector array can be coupled with recoil detection to provide a full kinematic description of the reaction. To date, the device has been used to study reactions with light radioactive beams of 12B [3] and 15C [4], through to medium and heavy stable beams of 86Kr and 130,136Xe, respectively. The potential of such a device for exploitation with radioactive beam programmes, for example CARIBU at ANL [5], and around the world, is demonstrated.
This work was supported by the U.S. Department of Energy, Office of Nuclear Physics under Contract No. DE-AC02-06CH11357 and Grant No. DE-FG02-04ER41320, and NSF Grant No. PHY-02-16783.
[1] A. H. Wuosmaa et al., Nucl. Instrum. Methods Phys. Res. Sect. A 580, 1290 (2007).
[2] J. C. Lighthall et al., Nucl. Instrum. Methods Phys. Res. Sect. A 622, 97 (2010).
[3] B. B. Back et al., Phys. Rev. Lett. 104, 132501 (2010).
[4] A. H. Wuosmaa et al., Phys. Rev. Lett. 105, 132501 (2010).
[5] G. Savard et al., Nucl. Instrum. Methods Phys. Res. Sect. B 266, 4086 (2008).
Author
Dr
Benjamin Kay
(Argonne National Laboratory)
