High Efficiency Positron Accumulation for High-Precision Measurements

Positrons are accumulated within a Penning trap designed to make more precise measurements of the positron and electron magnetic moments. The retractable radioactive source used is weak enough to require no license for handling radioactive material and the radiation dosage one meter from the source gives an exposure several times smaller than the average radiation dose on the earth's surface. The 100 mK trap is mechanically aligned with the 4.2 K superconducting solenoid that produces a 6 tesla magnetic trapping field with a direct mechanical coupling.Comment: 7 pages, 9 figure

Design and Assembly of a Large-aperture Nb3Sn Cos-theta Dipole Coil with Stress Management in Dipole Mirror Configuration

The stress-management cos-theta (SMCT) coil is a new concept which has been proposed and is being developed at Fermilab in the framework of US Magnet Development Program (US-MDP) for high-field and/or large-aperture accelerator magnets based on low-temperature and high-temperature superconductors. The SMCT structure is used to reduce large coil deformations under the Lorentz forces and, thus, the excessively large strains and stresses in the coil. A large-aperture Nb3Sn SMCT dipole coil has been developed and fabricated at Fermilab to demonstrate and test the SMCT concept including coil design, fabrication technology and performance. The first SMCT coil has been assembled with 60-mm aperture Nb3Sn coil inside a dipole mirror configuration and will be tested separately and in series with the insert coil. This paper summarizes the large-aperture SMCT coil design and parameters and reports the coil fabrication steps and its assembly in dipole mirror configuration

Quench Protection Study of a Single-Aperture 11 T Nb3Sn Demonstrator Dipole for LHC Upgrades

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Field Quality Measurements in a Single-Aperture 11 T Nb3Sn Demonstrator Dipole for LHC Upgrades

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Development of Nb3Sn 11 T single aperture demonstrator dipole for LHC upgrades

The LHC collimation upgrade foresees additional collimators installed in dispersion suppressor regions. To obtain the necessary space for the collimators, a solution based on the substitution of LHC main dipoles for stronger dipoles is being considered. CERN and FNAL have started a joint program to demonstrate the feasibility of Nb{sub 3}Sn technology for this purpose. The goal of the first phase is the design and construction of a 2-m long single-aperture demonstrator magnet with a nominal field of 11 T at 11.85 kA with 20% margin. This paper describes the magnetic and mechanical design of the demonstrator magnet and summarizes its design parameters

Fabrication and test of 4m long Nb3Sn quadrupole coil made of RRP-114-127 strand

Fermilab is collaborating with LBNL and BNL (US-LARP collaboration) to develop a large-aperture Nb{sub 3}Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade. Several two-layer quadrupole models of the 1-meter and 3.4-meter length with 90mm apertures have been fabricated and tested by the US-LARP collaboration. High-Jc RRP-54/61 strand was used for nearly all models. Large flux jumps typical for this strand due to the large sub-element diameter limited magnet quench performance at temperatures below 2.5-3K. This paper summarizes the fabrication and test by Fermilab of LQM01, a long quadrupole coil test structure (quadrupole mirror) with the first 3.4m quadrupole coil made of more stable RRP-114/127 strand. The coil and structure are fully instrumented with voltage taps, full bridge strain gauges and strip heaters to monitor preload, thermal properties and quench behavior. Measurements during fabrication are reported, including preload during the yoke welding process. Testing is done at 4.5K, 1.9K and a range of intermediate temperatures. The test results include magnet strain and quench performance during training, as well as quench studies of current ramp rate and temperature dependence from 1.9K to 4.5K

RHQT Nb3Al 15-Tesla magnet design study

Feasibility study of 15-Tesla dipole magnets wound with a new copper stabilized RHQT Nb{sub 3}Al Rutherford cable is presented. A new practical long copper stabilized RHQT Nb{sub 3}Al strand is presented, which is being developed and manufactured at the National Institute of Material Science (NIMS) in Japan. It has achieved a non-copper J{sub c} of 1000A/mm{sup 2} at 15 Tesla at 4.2K, with a copper over non-copper ratio of 1.04, and a filament size less than 50 microns. For this design study a short Rutherford cable with 28 Nb{sub 3}Al strands of 1 mm diameter will be fabricated late this year. The cosine theta magnet cross section is designed using ROXIE, and the stress and strain in the coil is estimated and studied with the characteristics of the Nb{sub 3}Al strand. The advantages and disadvantages of the Nb{sub 3}Al cable are compared with the prevailing Nb{sub 3}Sn cable from the point of view of stress-strain, J{sub c}, and possible degradation of stabilizer due to cabling. The Nb{sub 3}Al coil of the magnet, which will be made by wind and react method, has to be heat treated at 800 degree C for 10 hours. As preparation for the 15 Tesla magnet, a series of tests on strand and Rutherford cables are considered

Quench performance of Nb3Sn cos-theta coils made of 108/127 RRP strands

A series of 1-m long Nb{sub 3}Sn dipole models has been built at Fermilab in an attempt to refine the wind-and-react technology for Nb3Sn accelerator magnets. Three models made with Powder-in-Tube Nb{sub 3}Sn strand reached their design field of 10 T demonstrating a good reproducibility of magnet quench performance and field quality. Recently a new dipole 'mirror' model based on Nb{sub 3}Sn coil made of improved Restack Rod Process strand was constructed and tested reaching the maximum field above 11 T. This paper describes the parameters of the RRP strand and cable used as well as the design, fabrication and test results of this magnet