[en] We present recent measurements of the CKM angles alpha and gamma using data collected by the BaBar detector at the PEP-II asymmetric-energy e⁺e^- collider at the Stanford Linear Accelerator Center. In addition to constraints on alpha from the decays B0 → π⁺π^-, B0 → ρ⁺ π^- and B0 → ρ⁺ρ^-, we also report the first measurement of time-dependent CP asymmetries in the decay B0 → a1⁺(1260) π^-. We present measurements of gamma in B+ → D(*)0 K+ decays using a Dalitz analysis in the modes D⁰ → Ks π⁺π^- and D⁰ → π⁺π^-π⁰. We present recent measurements of the CKM angles alpha and gamma using data collected by the BaBar detector at the PEP-II asymmetric-energy e⁺e^- collider at the Stanford Linear Accelerator Center. In addition to constraints on alpha from the decays B0 -> π⁺π^-, B0 → ρ⁺ π^- and B0 → ρ⁺ρ^-, we also report the first measurement of time-dependent CP asymmetries in the decay B0 → a1⁺(1260) π^-. We present measurements of gamma in B⁺ → D(*)0 K+ decays using a Dalitz analysis in the modes D⁰ → Ks π⁺π^- and D⁰ → π⁺π^-π⁰

[en] Design studies for the cooling channel of a Muon Collider call for straight and helical solenoids generating field well in excess of the critical fields of state of the art Low Temperature Superconductors (LTS) such as Nb₃Sn or NbTi. Therefore, High Temperature Superconductors (HTS) will need to be used for the manufacturing of all or certain sections of such magnets to be able to generate and withstand the field levels at the cryogenic temperatures required by the new machine. In this work, two major High Temperature Superconductors - Bi2212 round wires and YBCO coated conductor tapes - are investigated to understand how critical current density of such conductors scales as a function of external field and operating temperature. This is vital information to make conductor choices depending on the application and to proceed with the design of such magnets.

[en] Superconducting magnets with magnetic fields above 20 T will be needed for a Muon Collider and possible LHC energy upgrade. This field level exceeds the possibilities of traditional Low Temperature Superconductors (LTS) such as Nb₃Sn and Nb₃Al. Presently the use of high field high temperature superconductors (HTS) is the only option available for achieving such field levels. Commercially available YBCO comes in tapes and shows noticeable anisotropy with respect to field orientation, which needs to be accounted for during magnet design. In the present work, critical current test results are presented for YBCO tape manufactured by Bruker. Short sample measurements results are presented up to 14 T, assessing the level of anisotropy as a function of field, field orientation and operating temperature.

[en] The final beam cooling stages of a Muon Collider may require DC solenoid magnets with magnetic fields of 30-50 T. In this paper we present progress in insert coil development using commercially available YBa₂Cu₃O_7-δ Coated Conductor. Technological aspects covered in the development, including coil geometry, insulation, manufacturing process and testing are summarized and discussed. Test results of double pancake coils operated in liquid nitrogen and liquid helium are presented and compared with the performance of YBa₂Cu₃O_7-δ tape short samples.

[en] The design of a variable-temperature probe used to perform strain sensitivity measurements on LTS wires and HTS wires and tapes is described. The measurements are intended to be performed at liquid helium temperatures (4.2 K). The wire or tape to be measured is wound and soldered on to a helical spring device, which is fixed at one end and subjected to a torque at the free end. The design goal is to be able to achieve ± 0.8 % strain in the wire and tape. The probe is designed to carry a current of 2000A.

[en] The final beam cooling stages of a Muon Collider may require DC solenoid magnets with magnetic fields in the range of 40-50 T. In this paper we will present a modular test facility developed for the purpose of investigating very high field levels with available 2G HTS superconducting materials. Performance of available conductors is presented, together with magnetic calculations and evaluation of Lorentz forces distribution on the HTS coils. Finally a test of a double pancake coil is presented.

[en] The ROEBEL cable concept allows for a high critical current cable assembled using commercially available YBa₂Cu₃O_7-δ coated conductors. this approach to cable design leads to several technological improvements if applied to the manufacture process of next generation low inductance, high current density HTS coils. A reduction in inductance proves to be extremely important when it comes to protection of coils capable of generating fields in the range of 40-50T, such as the ones needed in the last stage of the cooling channel of a muon collider. In this work several aspects are presented including the qualification and minimum requirements for YBa₂Cu₃O_7-δcoated conductor in terms of 2D current density uniformity and the manufacturing process of ROEBEL cables. Test results achieved using a superconducting transformer for critical current measurements in liquid helium are shown, discussed and compared to the performance of a single YBa₂Cu₃O_7-δ coated conductor tape.

[en] An experiment is in the works at Fermilab to confirm that ionization cooling is an efficient way to shrink the size of a muon beam. This would pave the way for Muon Collider machines, which however require in their last stages of acceleration very high field solenoids. The use of high temperature superconducting materials (HTS) is being considered for these magnets using Helium or higher temperature refrigeration. A sample holder was designed to perform critical current (I_c) measurements of HTS conductors under externally applied magnetic fields varying from zero to 90 degree with respect to the c-axis. This was performed in an ample range of temperatures and magnetic field values. A description of the test setup and results for (Bi,Pb)₂Sr₂Ca₂Cu₃O_x (BSCCO-2223) tapes, and Second Generation HTS in the form of 348 superconductor are presented

[en] A major thrust in Fermilab's accelerator magnet R and D program is the development of Nb₃Sn wires which meet target requirements for high field magnets, such as high critical current density, low effective filament size, and the capability to withstand the cabling process. The performance of a number of strands with 150/169 restack design produced by Oxford Superconducting Technology was studied for round and deformed wires. To optimize the maximum plastic strain, finite element modeling was also used as an aid in the design. Results of mechanical, transport and metallographic analyses are presented for round and deformed wires.

[en] Fermilab's cabling facility has been upgraded to a maximum capability of 42 strands. This facility is being used to study the effect of cabling on the performance of the various strands, and for the development and fabrication of cables in support of the ongoing magnet R and D programs. Rutherford cables of various geometries, packing factors, with and without a stainless steel core, were fabricated out of Cu alloys, NbTi, Nb₃Al, and various Nb₃Sn strands. The parameters of the upgraded cabling machine and results of cable R and D efforts at Fermilab are reported