The SEparator for CApture Reactions (SECAR) is a next-generation recoil separator system under construction in the ReA3 Hall at the National Superconducting Cyclotron Laboratory and Facility for Rare Isotope Beams (FRIB) at Michigan State University. Click on the image to see the entire system. SECAR is optimized for the direct measurement of capture reactions on unstable nuclei that drive some stars to explode and synthesize crucial nuclei that make up our bodies and our world. The SECAR Project includes work to design, procure, install, and commission this unique system at ReA3. The project is scheduled for completion in 2021, at which time the SECAR Collaboration and other researchers will utilize SECAR for measurements to improve our understanding of novae, X-ray bursts, supernovae, and other explosive and exotic astrophysical environments.
FRIB will be hosting a VIRTUAL hands-on workshop on May 4 - 8, 2020 to support the preparation of proposals for consideration by the first FRIB Program Advisory Committee. The "FRIB First Experiments: Proposal Preparation" workshop be held at FRIB in East Lansing, MI. Please visit https://indico.frib.msu.edu/event/20/ for more details. There will be a session focussed on SECAR and JENSA on Wednesday, May 6 at 16:00 EDT.
Planned beamtime for SECAR early commissioning runs in mid-March to May are delayed due to the pandemic. Please check back on this page for updates on when the laboratory will re-open and when beamtimes will be rescheduled.
SECAR early commissioning continued with a run in early March. Successes include: procedures for beam tuning; calibration of the first two SECAR dipoles; testing of an initial set of diagnostic devices including viewers and ammeters; testing of the SECAR/JENSA BGO gamma array; and testing of the data acquisition system.
The sixth annual SECAR Project review will be held from June 11-12, 2020.
Proposals for beam time at NSCL during the transition to FRIB were due on January 9, 2020, and the ReA-PAC meeting was held March 3-4, 2020. We expect SECAR to be completed and available for experiments during the NSCL-to-FRIB transition period. The list of available beams is posted at https://nscl.msu.edu/users/beams.html, and a webinar with details on this process can be found online at https://fribusers.org/news.html#webinar2019. The SECAR Collaboration submitted a proposal for commissioning, as well as a number of science proposals.
SECAR early commissioning began and has already resulted in a number of successes, including: beam line and associated diagnostics commissioned up to Focal Plane 2 (FP2); beam shape and size at FP2 (2mm wide x 4mm tall) shown consistent with ion optical calculations; first magnet calibration data point taken for dipoles B1 and B2 using a resonance in proton capture on 27Al + p resonances; transmission measured from target to FP1; first use of the SECAR BGO gamma detection array at the target location; and development of an efficient and reproducible tuning procedure to transport the beam along the ion optical axis to FP2.
The SECAR Project team successfully completed their fifth annual project review.
Several SECAR commissioning experiments were scheduled in April
and May 2020 that will need to be rescheduled due to the
temporary closure of the laboratory as a response to the pandemic.
These runs include:
- Dipole energy calibration (continuation)
- Beam tuning up to FP2 with WF1
- Beam tuning up to FP3 with WF1
- Beam tuning to FP4 with FP detectors
- Beam tuning to FP4 with H/He gas target
- Charge state studies with H/He gas target
- Jet target thickness measurements with H/He
The next SECAR Project Review is still scheduled on 6/11/20 - 6/12/20.
All of these dates are subject to change based on the facility status. Please check the SECAR Calendar for the latest updates. If using a mobile device, please check the Agenda view shown on the SECAR Mobile Calendar.
"Design of SECAR: a Recoil Mass Separator for Astrophysical
Capture Reactions with Radioactive Beams" by G. Berg, M. Couder,
M.T. Moran, K. Smith, M. Wiescher, H. Schatz, U. Hager, C. Wrede,
F. Montes, G. Perdikakis, X. Wu, A. Zeller, M.S. Smith, D.W. Bardayan,
K.A. Chipps, S.D. Pain, J. Blackmon, U. Greife, K.E. Rehm, and R.V.F. Janssens,
Nuclear Instruments and & Methods A 877, (2018) 87-103.
The SECAR Project is funded by the
Office of Nuclear Physics in the
U.S. Department of Energy Office of Science
National Science Foundation.
Contributions were also made by:
SECAR will be used to advance our understanding of stellar explosions including novae, X-ray bursts, and supernovae, as well as other exotic astrophysical sites including supermassive stars, hypernovae, Thorne-Zytkow objects, and the very first stars in the Universe. By facilitating direct measurement of reactions on unstable isotopes, SECAR will establish an empirical foundation for simulations of the element creation and energy generation occurring in these fascinating astrophysical systems. For additional details, please see this document on science with SECAR from the 2014 SECAR pre-Conceptual Design Report.
The manuscript "Design of SECAR: a Recoil Mass Separator for Astrophysical Capture Reactions with Radioactive Beams" by G. Berg, M. Couder, M.T. Moran, K. Smith, M. Wiescher, H. Schatz, U. Hager, C. Wrede, F. Montes, G. Perdikakis, X. Wu, A. Zeller, M.S. Smith, D.W. Bardayan, K.A. Chipps, S.D. Pain, J. Blackmon, U. Greife, K.E. Rehm, and R.V.F. Janssens was published in Nuclear Instruments and & Methods A 877, (2018) 87-103.
The SECAR system consists of 8 Dipole Magnets (red components in the diagram), 15 Quadrupole Magnets (yellow), 5 Multipole Magnets (light blue), and two Velocity Filters (dark blue). The first set of dipole magnets in SECAR performs a critical charge-state selection of both the recoils and unreacted projectiles that enter the SECAR system. The primary projectile rejection components of SECAR are the two Velocity Filters. These devices, also known as Wien Filters, have a vertical magnet field B and a horizontal electric field E that together serve to deflect the trajectory of any particles with a velocity different than E/B. By appropriately tuning these fields, the unreacted beam particles that enter the system can be deflected away while the reaction products of interest (recoils) are passed through to eventually reach the focal plane. Since the unreacted beam particles have an intensity of 1013 - 1017 higher than the capture reaction recoils of interest, the SECAR design includes two Velocity Filters to obtain the level of projectile rejection needed to enable the identification of capture reaction recoils at the SECAR focal plane, and thereby enable the measurement of critical capture reactions on unstable nuclei that power certain types of stellar explosions. More information on the separator can be found in the this SECAR Project Update presentation by Hendrik Schatz (May 2020).
The SECAR focal plane features two microchannel plate (MCP) detectors followed by a position-sensitive gas ionization counter. The first detectors will determine the ion velocity by their time of flight, and the second detector will determine the ion atomic number Z by measuring their differential energy loss and total energy loss (dE-E) in the detector gas. The focal plane is designed to give an additional factor of 104 separation of scattered projectile background and capture reaction recoils beyond that provided by the separator magnets and velocity filters.
The Jet Experiments for Nuclear Structure and Astrophysics (JENSA) system provides 4mm-wide ultra-dense jets of hydrogen and helium gas that serve as the target for capture reactions measurements with SECAR. The high densities possible with JENSA -- over 1019   atoms/cm2 with He -- and the elimination of reactions off of backing materials commonly found in foil targets, makes this gas jet system ideally suited for our experiments. JENSA also functions as a windowless extended gas target that enables searches for resonances with unknown energies to be carried out. Once located, complimentary, higher-resolution studies can be carried out with the jet target. More information on JENSA can be found in this JENSA update presentation by Kelly Chipps (May 2020). Also, please visit the JENSA web site for more details.
The SECAR Project, jointly funded by DOE and NSF, is slated for completion in 2021. The organizational chart of the project is shown. Please check the News and Highlights sections above for details on the progress of the project. After completion, the system will be used by the SECAR Collaboration and other researchers to measure reactions that are needed to understand novae, X-ray bursts, and other exploding stars.
The SECAR Collaboration is an open, active collaboration of
researchers who are passionate about measuring thermonuclear reactions
that drive some stars to explode. Please
if you are interested in contributing to our
separator system or by
submitting a proposal to
enhance our scientific program.
As the SECAR Project nears completion in late 2020, we are transitioning the SECAR Collaboration from focusing on completion of system installation and commissioning to focusing on proposing, running, and analyzing experiments. We are in the process of establishing a collaboration agreement to codify the activities and organizational structure of the collaboration. We will post the collaboration agreement here when finalized.
Please click here to learn more about submitting a proposal with the SECAR system.