The FMA is located at the ATLAS accelerator at Argonne National Laboratory. It is used to separate nuclear reaction products from the primary heavy ion beam and disperses them by mass/charge (M/q) at the focal plane.

The FMA features wide acceptances in particle energy and M/q, as well as high mass resolution. Magnetic and electric fields (up to 500 kV across a 10 cm gap) are used to guide the desired particles and focus them onto detectors at the focal plane. The FMA rotates about a pivot directly under the target position, although for most experiments it is positioned at 0 degrees to the beam direction.

A wide variety of experiments can be performed at the FMA. High-spin spectroscopy can be conducted by using an array of gamma-ray detectors around the target and tagging each event with the M/q of the recoil nucleus as determined at the focal plane. Both recoil-gamma and recoil-gamma-gamma coincidences have been measured in this way. In the past, FMA was used in conjunction with Argonne’s large arrays of germanium detectors, Gammasphere and GRETINA.

At the focal plane, studies of exotic alpha and proton decays can be carried out with the implantation facility using a double-sided silicon strip detector (DSSD). In addition, a moving tape collector is available for measurements of beta radioactivity. Studies of microsecond isomers can be performed using gamma and electron detectors at the focal plane.

Selected Publications

• Proton decay of ¹⁰⁸I and its significance for the termination of the astrophysical rp-process 
  K. Auranen, D. Seweryniak, M. Albers et al., Phys. Lett. B 792, 187 (2019)
• Superallowed alpha decay to doubly magic ¹⁰⁰Sn
  K. Auranen, D. Seweryniak, M. Albers et al., Phys. Rev. Lett. 121, 182501 (2019)
• Decay and fission hindrance of two- and four-quasiparticle isomers in ²⁵⁴Rf 
  H. M. David, J. Chen, D. Seweryniak et al., Phys. Rev. Lett. 115, 132502 (2015)
• Structure of Resonances in the Gamow Burning Window for the ²⁵Al(p,γ)²⁶Si Reaction in Novae
  D. T. Doherty, P. J. Woods, D. Seweryniak et al., Phys. Rev. C 92, 035808 (2015)
• Fission Barrier of Superheavy Nuclei and Persistence of Shell Effects at High Spin: Cases of ²⁵⁴No and ²²⁰Th
  G. Henning, T. L. Khoo, A. Lopez-Martens et al., Phys. Rev. Lett. 113, 262505 (2014)
• First in-beam gamma-ray spectroscopy study of ²⁴Al and its implications for the astrophysical ²³Mg(p,γ)²⁴Al rate in ONe novae
  G. Lotay, P. J. Woods, D. Seweryniak et al., Phys. Rev. C 77, 042802(R) (2008)
• Single-Neutron States in ¹⁰¹Sn
  D. Seweryniak, M. P. Carpenter, S. Gros et al., Phys. Rev. Lett. 99, 022504 (2007)
• Effect of a Triaxial Nuclear Shape on Proton Tunneling: the Decay and Structure of ¹⁴⁵Tm
  D. Seweryniak, B. Blank, M. P. Carpenter et al., Phys. Rev. Lett. 99, 082502 (2007)
• Level structure of ²⁶Si and its implications for the astrophysical reaction rate of ²⁵Al(p,γ)²⁶Si
  D. Seweryniak, P. J. Woods, M. P. Carpenter et al., Phys. Rev. C 75, 062801(R) (2007)
• Alpha Decay of ¹⁰⁵Te
  D. Seweryniak, K. Starosta, C. N. Davids et al., Phys. Rev. C 73, 061301(R) (2006)
• K-isomers in ^254No: Probing Single Particle Energies and Pairing Strengths in the Heaviest Nuclei
  S. K. Tandel, T. L. Khoo, D. Seweryniak et al., Phys. Rev. Lett 97, 082502 (2006)