[en] A wide variety of temperature/processing changes and high energy irradiation has substantially increased B_t,max. This plus variation of the HTS mix to Y_1.7Ba₂Cu₃O₇Pt_0.01U²³⁵(25 ppM) has increased trapped field by a factor of 8 and promises an additional factor of 2. The original goal, to produce 10,000 Gauss of trapped field, has been exceeded by a factor of 7. Various applications, including motors, generators, levitating bearings, flywheels, magnetic bumpers, and MHD propulsion are in progress at various labs and industries

[en] Fast kicker magnets are needed in accelerators to deflect the beam out of the storage ring and into experimental targets and beam dumps. The work reported here is on a new type of fast kicker magnet. The basic idea is to transport the beam along the axis of a tube made of Type I superconductor. An ordinary magnet is used to create a field, B_o perpendicular to the axis of the tube. If B_o< B_c, where B_c is the critical field of the superconductor, the tube remains in the superconducting condition. Due to the Meissner effect, the tube shields the beam (on the axis of the tube) from B_o. Thus the beam is in a zero field region. In order to apply a kicker field to the beam, B_o is increased such that B_o>B_c. The tube of superconductor then goes normal. The field which had been shielded from the beam can now penetrate to the beam. This concept is applicable as a fast magnetic switch. DOE has been granted a patent on this device, which was disclosed to DOE by N.K. Mahale and D. Goren while they were at SSC. A feasibility study of this new form of kicker magnet is reported here

[en] Despite tremendous progress in recent years in measuring single nucleon momentum distributions in nuclei, two-nucleon momentum distributions remain largely unmeasured. Here we report on a measurement of 3He(e,epp)n that is primarily sensitive to the two-nucleon momentum distribution and relatively uncontaminated by final state rescattering or by two-body currents

[en] Dimuon production is reported for the reaction π^- + Fe → μ⁺ + μ^- + anything at 200 GeV and p + Fe → μ⁺ + μ^- anything at 240 GeV. The X/sub L/ identical with P/sub L//P/sub Beam/ and P/sub perpendicular/ dependences of psi production are parameterized and fitted. For X/sub L/ greater than or equal to 0.5, the ratio of the psi production cross section for pions in iron to that for protons is found to be 7.4 +- 2. For the intermediate mass region, 1.2 less than or equal to M less than or equal to 2.5 GeV, preliminary results are given for X/sub L/, P/sub perpendicular/ and M/sub mu mu/ dependences

[en] We have measured the ³He(e,e'pp)n reaction in the Jefferson Lab CLAS with 2.2 and 4.4 GeV electrons. We looked at the energy distribution of events with all three nucleons at high momentum (p > 250 MeV/c). This distribution has peaks where two nucleons each have 20% or less of the energy transfer (ie: the third or 'leading' nucleon carries most of the kinetic energy). The angular distribution of these two 'fast' nucleons shows a very large back-to-back peak, indicating the effect of correlations. While there is some theoretical disagreement, experimental evidence, plus calculations at lower energy by W. Glockle, indicates that these events are primarily sensitive to NN correlations

[en] Recent results from PEP are presented. In electroweak interactions the measured charge asymmetries for ee→μμ,tau tau, and ee are reported. Results are given for lifetime measurements of the tau lepton, D⁰ meson, and b quark, and measured branching ratios for the tau are given. QED tests of the electron propagator and muon compton scattering are reported. In strong interactions, measurements are reported for R, and Energy-Energy Correlation measurements of α/sub s/ are given. Flavor tagging measurements are reported, including multiplicity and α/sub s/ for samples enriched in c and b, and fragmentation functions are reported for c and for b. The results of searches are also presented for 10 postulated particles

[en] The suitability of open-profile CSCs for the GEM muon system was evaluated by constructing a small (0.5 m x 1.0 m) prototype and testing it with cosmic ray muons. The measured spatial resolution surpassed the GEM requirement of 75 μm. The test results were compared with Monte Carlo simulations; good agreement was found. Studies of the timing properties of the prototype have been started

[en] A program has been pursued to develop materials, processing, and applications for high temperature superconducting permanent magnets. The trapped field, B_t ∼ J_cf(d), where J_c is the critical current, and f(d) is a monotonically increasing function of the diameter, d, of a single grain. Early experiments resulted in B_t ∼ 3 x 10^-5 Tesla. As a result of increasing J_c and d, a mini-magnet 1.2 x 1.2 x 1.5 cm³ now traps 1.52 Tesla at 77 K. Fields up to 1.9 T have been achieved at lower temperatures. In the interval 20 K ≤ T₁, T₂ ≤ 65 K, temperature dependence is: B_t(T₂) = B_t(T₁)(T_c-T₂/T_c-T₁)². A mini-magnet which traps, e.g., 2T at 65K should trap over 14 T at 20 K. However, at about 8 T the authors expect the onset of local quenching, and cracking under magnet pressure. A large part of the increase in J_c has been achieved by cyclotron irradiation. Proton fluences of 1.8 x 10¹⁶/cm², and 3He⁺⁺ or 4He⁺⁺ fluences of 6 x 10¹⁵/cm², are near optimum. The increase in J_c, and hence B_t, achieved by H⁺ and He⁺⁺ bombardment is about a factor of 4. Bombardment by higher Z appears to improve J_c even more effectively. A two component theoretical model of the persistent currents has been developed

[en] Critical currents J_c(T,B) for virgin and four ²³⁵U doped Bi2223/Ag tapes irradiated with thermal neutrons (U/n treated) were measured in the temperature range T≥50 K and magnetic field B≤1 T. Below 97 K vortex pinning in U/n treated tapes increases with matching field B_phi, as evidenced by a weaker B dependence of J_c on increasing B_phi. Hence, the field B_max (F_pmax=J_cB_max) and the irreversibility field B_irr(F_p → 0) of U/n treated tapes are enhanced compared to those for virgin tape. Since the rate of the enhancement of B_max and B_irr with B_phi depends on T, one can tune the maximum enhancement at desired T

[en] The magnetoresistance R(T,B) of virgin and four ²³⁵U doped Bi2223/Ag tapes irradiated with thermal neutrons (U/n treated) has been measured in the temperature range T≥50 K and magnetic field B≤1 T. For B≥20 mT the pinning potentials U₀ of U/n treated tapes were enhanced compared to that of virgin tape. The relative enhancement U₀(B,U/n)/U₀(B, virg.) increased with matching field B_phi and persisted to higher B at higher B_phi. For U/n treated samples, U₀ showed universal variation with B/B_phi: U₀(B≤B_phi)∝(B_phi/B)^α with α∼0.5 and faster variation at higher B. The resistive irreversibility fields B_irr(T) of all U/n treated samples for T≤100 K were also enhanced: B_irr(T,U/n)/B_irr(T, virg.) increased with B_phi and the enhancement persisted to lower T for higher B_phi. The maximum enhancements of B_irr scale well with the corresponding enhancements of U₀(B)