131 research outputs found
Evaluation of the discrete vortex wake cross flow model using vector computers. Part 2: User's manual for DIVORCE
The users manual for the Discrete Vortex Cross flow Evaluator (DIVORCE) computer program is presented. DIVORCE was developed in FORTRAN 4 for the DCD 6600 and CDC 7600 machines. Optimal calls to a NASA vector subroutine package are provided for use with the CDC 7600
Spin decoherence and off-resonance behavior of radiofrequency-driven spin rotations in storage rings
Radiofrequency-driven resonant spin rotators are routinely used as standard
instruments in polarization experiments in particle and nuclear physics.
Maintaining the continuous exact parametric spin-resonance condition of the
equality of the spin rotator and the spin precession frequency during operation
constitutes one of the challenges. We present a detailed analytic description
of the impact of detuning the exact spin resonance on the vertical and the
in-plane precessing components of the polarization. An important part of the
formalism presented here is the consideration of experimentally relevant
spin-decoherence effects. We discuss applications of the developed formalism to
the interpretation of the experimental data on the novel pilot bunch approach
to control the spin-resonance condition during the operation of the
radiofrequency-driven Wien filter that is used as a spin rotator in the first
direct deuteron electric dipole moment measurement at COSY. We emphasize the
potential importance of the hitherto unexplored phase of the envelope of the
horizontal polarization as an indicator of the stability of the
radiofrequency-driven spin rotations in storage rings. The work presented here
serves as a satellite publication to the work published concurrently on the
proof of principle experiment about the so-called pilot bunch approach that was
developed to provide co-magnetometry for the deuteron electric dipole moment
experiment at COSY.Comment: 31 pages, 10 figures, 5 table
Pilot bunch and co-magnetometry of polarized particles stored in a ring
In polarization experiments at storage rings, one of the challenges is to
maintain the spin-resonance condition of a radio-frequency spin rotator with
the spin-precessions of the orbiting particles. Time-dependent variations of
the magnetic fields of ring elements lead to unwanted variations of the spin
precession frequency. We report here on a solution to this problem by shielding
(or masking) one of the bunches stored in the ring from the high-frequency
fields of the spin rotator, so that the masked pilot bunch acts as a
co-magnetometer for the other signal bunch, tracking fluctuations in the ring
on a time scale of about one second. While the new method was developed
primarily for searches of electric dipole moments of charged particles, it may
have far-reaching implications for future spin physics facilities, such as the
EIC and NICA.Comment: 5 pages, 3 figures + references + supplemental material (6 pages, 2
figures, 6 tables + references
Self-healing response in supramolecular polymers based on reversible zinc–histidine interactions
Abstract Histidine-metal interactions are utilized in many biological materials as reinforcing crosslinks, and in particular, are believed to contribute as reversible crosslinks to the intrinsic self-recovery behavior of mussel byssal threads. In this contribution, two new histidine-based monomers were synthesized and further copolymerized with butyl methacrylate (BMA) and lauryl methacrylate (LMA) applying the reversible addition–fragmentation chain transfer (RAFT) polymerization technique. Crosslinking with zinc ions resulted in supramolecular metallopolymer networks exhibiting a self-healing behavior that was tunable depending on the specific zinc salt used. The presented results provide a class of new polymeric species with different self-healing capacities
- …