Giles Barr

Abstract:

The focusing solenoids for MICE surround energy absorbers that are used to reduce the transverse momentum of the muon beam that is being cooled within MICE. The focusing solenoids will have a warm-bore diameter of 470 mm. Within this bore is a flask of liquid hydrogen or a room temperature beryllium absorber. The focusing solenoid consists of two coils wound with a copper matrix Nb-Ti conductor originally designed for MRI magnets. The two coils have separate leads, so that they may be operated at the same polarity or at opposite polarity. The focusing magnet is designed so that it can be cooled with a pair of 1.5 W (at 4.2 K) coolers. The MICE cooling channel has three focusing magnets with their absorbers. The three focusing magnets will be hooked together in series for a circuit stored-energy of about 9.0 MJ. Quench protection for the focusing magnets is discussed. This report presents the mechanical and thermal design parameters for this magnet, including the results of finite element calculations of mechanical forces and heat flow in the magnet cold mass.

Abstract:

The decay rate of the long-lived neutral K meson into the e +e-e+e- final state has been measured with the NA48 detector at the CERN SPS. Using data collected in 1998 and 1999, a total of 200 events has been observed with negligible background. This observation corresponds to a branching ratio of Br(KL→ e+e-e+e-)=(3.30±0.24 stat±0.23syst±0.10norm) ×10-8. © 2005 Elsevier B.V. All rights reserved.

Abstract:

Using data taken during the year 2000 with the NA48 detector at the CERN SPS, a search for the CP violating decay KS→3π⁰ has been performed. From a fit to the lifetime distribution of about 4.9 million reconstructed K⁰/K̄⁰→3π⁰ decays, the CP violating amplitude η000=A(KS→3π⁰)/ A(KL→3π⁰) has been found to be Re(η000)=-0.002±0.011±0.015 and Im(η000)=-0.003±0. 013±0.017. This corresponds to an upper limit on the branching fraction of Br(KS→3π⁰)<7.4×10^-7 at 90% confidence level. The result is used to improve knowledge of Re(ε) and the CPT violating quantity Im(δ) via the Bell-Steinberger relation. © 2005 Elsevier B.V. All rights reserved.

Abstract:

We present a measurement of the relative branching ratio of the decay K⁰ → π^±e^±νγ (Ke3γ) with respect to K⁰ → π^±e^±ν (Ke3 + K e3γ) decay. The result is based on observation of 19 000 K e3γ and 5.6 × 10⁶ Ke3 decays. The value of the branching ratio is Br(Ke3γ⁰, E γ* > 30 MeV, θeγ* > 20°)/Br(Ke3⁰) = (0.964±0.008 -0.009^+0.011)%. This result agrees with theoretical predictions but is at variance with a recently published result. © 2004 Elsevier B.V. All rights reserved.

Abstract:

This report describes the focusing solenoid for the proposed Muon Ionization Cooling Experiment (MICE) [1]. The focusing solenoid consists of a pair of superconducting solenoids that are on a common bobbin. The two coils, which have separate leads, may be operated in the same polarity or at opposite polarity. This report discusses the superconducting magnet design and the cryostat design for the MICE focusing module. Also discussed is how this superconducting magnet can be. integrated with a pair of small 4.2 K coolers.