P. Benoit

On-Surface Test of the ATLAS Barrel Toroid Coils: Overview

The Barrel Toroid (BT) provides the magnetic field for the muon detectors in the ATLAS experiment at CERN. The Toroid is built up from eight superconducting coils. Each coil consists of two 25 m times 5 m racetrack shape double pancakes impregnated and pre-stressed inside an aluminum coil casing. The 42-tons cold mass is cooled by forced-flow liquid helium circulating in aluminum pipes glued to its surface. The coils are tested on surface prior to their underground installation. The test program has started in September 2004 and finished in June 2005. This paper describes the test set up and various commissioning tests performed at the ATLAS Magnet Test Facility. It includes the aspects of test preparation, vacuum pumping, leak testing, cooling down, powering and warming up. The 8 coils have passed the tests successfully and have been assembled into the Toroid in the ATLAS cavern. The testing completes the production of the so far largest racetrack coils in the world

First full-size ATLAS barrel toroid coil successfully tested up to 22 kA at 4 T

The Superconducting Barrel Toroid is providing (together with the two End-Cap Toroids not presented here) the magnetic field for the muon detectors in the ATLAS Experiment at the LHC at CERN. The toroid with outer dimensions of 25 m length and 20 m diameter, is built up from 8 identical racetrack coils. The coils with 120 turns each are wound with an aluminum stabilized NbTi conductor and operate at 20.5 kA at 3.9 T local field in the windings and is conduction cooled at 4.8 K by circulating forced flow helium in cooling tubes attached to the cold mass. The 8 coils of 25 m /spl times/ 5 m are presently under construction and the first coils have already been fully integrated and tested. Meanwhile the assembly of the toroid 100 m underground in the ATLAS cavern at CERN has started. The 8 coils are individually tested on surface before installation. In this paper the test of the first coil, unique in size and manufacturing technology, is described in detail and the results are compared to the previous experience with the 9 m long B0 model coil.

On-Surface Tests of the ATLAS Barrel Toroid Coils: Acceptance Criteria and Results

Each superconducting coil of the ATLAS Barrel Toroid has to pass the commissioning tests on surface before the installation in the underground cavern for the ATLAS Experiment at CERN. Particular acceptance criteria have been developed to characterize the individual coils during the on-surface testing. Based on these criteria and the limited time of the test, a compressed test program was proposed and realized. In only a few cases some additional tests were required to justify the coil performance and acceptance. In this paper the analysis of the test results is presented and discussed with respect to the acceptance criteria. Some differences in the parameters found between the identical coils are analyzed in relation to coil production features

ATLAS End Cap Toroid Integration and Test

The ATLAS Experiment at LHC, CERN will utilize a large, superconducting, air-cored toroidal magnet system with a long Barrel Toroid and two end cap toroids. Each end cap toroid will contain eight racetrack coils mounted as a single cold mass in a cryostat vessel of approximately 10 m diameter and 5 m width. The toroids provide the magnetic field for the muon detectors. The operating current is 20.5 kA at 0.25 GJ stored energy and a peak field of 4.1 T in the windings. This paper presents the status of the End Cap Toroid Project. Cold mass assembly and the integration of the full cold mass, 120 tons, into the vacuum cryostat for the first toroid are described. The specialized techniques, procedures and tooling infrastructure required for these operations are explained. The pre-installation cooldown to 77 K at the ATLAS cryogenic test facility is reported and the toroid installation in the ATLAS Experiment 100 m underground in the ATLAS cavern will be reviewed.

ATLAS End Cap Toroid Final Integration, Test and Installation

The ATLAS Experiment at LHC, CERN will utilize a large, superconducting, air-cored toroidal magnet system with a long Barrel Toroid and two End Cap Toroids. Each End Cap Toroid contains eight racetrack coils mounted as a single cold mass in a cryostat vessel of approximately 10 m diameter and 5 m length. The operating current is 20.5 kA at 0.25 GJ stored energy and a peak field of 4.1 T in the windings. This paper presents the status of the End Cap Toroid Project. Final integration of the two cold masses, 120 tons each, into their respective vacuum cryostats is described. The specialized techniques, procedures and tooling infrastructure required for these operations are explained. Pre-installation cooldown to 85 K is reported. Installation of the toroids in the ATLAS cavern 100 m underground will be described. The final interfacing to the Barrel Toroid and services in the cavern will be reviewed along with preparations for final test and commissioning.

Hot Spot in ATLAS Barrel Toroid Quenches

The ATLAS Barrel Toroid, the largest toroid ever built with 1.1 GJ stored energy, has been successfully tested after installation in the underground cavern in fall 2006. The eight coils of the Barrel Toroid were tested individually before and showed fully acceptable performances. We observed only one training quench during an individual coil test (at 30 A below the maximum test current) and no training during the test of the fully assembled toroid. At currents up to the nominal value of 20.5 kA, the toroid has been quenched inducing normal zones by means of heaters or by stopping the helium flow in the current leads. The quench safety system worked perfectly. Given the safe peak temperatures measured in the cold mass following various quenches, it is concluded that the Barrel Toroid can be operated safely. In this paper, the hot spot of the toroid is presented in detail: the measurement data are compared to various theoretical models.

Baby MIND: A magnetised spectrometer for the WAGASCI experiment

The WAGASCI experiment being built at the J-PARC neutrino beam line will measure the ratio of cross sections from neutrinos interacting with a water and scintillator targets, in order to constrain neutrino cross sections, essential for the T2K neutrino oscillation measurements. A prototype Magnetised Iron Neutrino Detector (MIND), called Baby MIND, has been constructed at CERN and will act as a magnetic spectrometer behind the main WAGASCI target. Baby MIND will be installed inside the WAGASCI cavern at J-PARC in the beginning of 2018. Baby MIND will be able to measure the charge and momentum of the outgoing muon from neutrino charged current interactions, to enable full neutrino event reconstruction in WAGASCI. During the summer of 2017, Baby MIND was operated and characterised at the T9 test beam at CERN. Results from this test beam will be presented, including charge identification performance and momentum resolution for charged tracks. These results will be compared to the Monte Carlo simulations. Finally, simulations of charge-current quasi-elastic (CCQE) neutrino interactions in an active scintillator neutrino target, followed by the Baby MIND spectrometer, will be shown to demonstrate the capability of this detector set-up to perform cross-section measurements under different assumptions.

The Baby MIND spectrometer for the J-PARC T59(WAGASCI) experiment

The Baby MIND spectrometer is designed to measure the momentum and charge of muons from neutrino interactions in water and hydrocarbon targets at the J-PARC T59 (WAGASCI) experiment. The WAGASCI experiment will measure the ratio of neutrino charged current interaction cross-sections on water and hydrocarbon aiming at reducing systematic errors in neutrino oscillation analyses at T2K. Construction of the Baby MIND detector within the CERN Neutrino Platform framework was completed in June 2017, where it underwent full commissioning and characterization on a charged particle beam line at the Proton Synchrotron experimental hall.

Baby MIND: A magnetized segmented neutrino detector for the WAGASCI experiment

T2K (Tokai-to-Kamioka) is a long-baseline neutrino experiment in Japan designed to study various parameters of neutrino oscillations. A near detector complex (ND280) is located 280 m downstream of the production target and measures neutrino beam parameters before any oscillations occur. ND280s measurements are used to predict the number and spectra of neutrinos in the Super-Kamiokande detector at the distance of 295 km. The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-cancelling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new WAter-Grid-And-SCintillator detector (WAGASCI) has been developed. A magnetized iron neutrino detector (Baby MIND) will be used to measure momentum and charge identification of the outgoing muons from charged current interactions. The Baby MIND modules are composed of magnetized iron plates and long plastic scintillator bars read out at the both ends with wavelength shifting fibers and silicon photomultipliers. The front-end electronics board has been developed to perform the readout and digitization of the signals from the scintillator bars. Detector elements were tested with cosmic rays and in the PS beam at CERN. The obtained results are presented in this paper.

Synchronization of the distributed readout frontend electronics of the Baby MIND detector

Baby MIND is a new downstream muon range detector for the WGASCI experiment. This article discusses the distributed readout system and its timing requirements. The paper presents the design of the synchronization subsystem and the results of its test.