136953526
Performances of large BGO crystals below 20 MeV
120234331
Performances of a preamplifier-silicon photodiode readout system associated with large BGO crystal scintillators
Abstract The characteristics of a hybridized low noise preamplifier are described. Performances of the preamplifier in combination with silicon photodiodes are discussed and results from laboratory tests and test runs with an assembly of large BGO crystals are presented.
118081032
A Simplified Cryogenic Distribution Scheme for the Large Hadron Collider
The Large Hadron Collider (LHC), currently under construction at CERN, will make use of superconducting magnets operating in superfluid helium below 2 K. The reference cryogenic distribution scheme was based, in each 3.3 km sector served by a cryogenic plant, on a separate cryogenic distribution line which feeds elementary cooling loops corresponding to the length of a half-cell (53 m). In order to decrease the number of active components, cryogenic modules and jumper connections between distribution line and magnet strings a simplified cryogenic scheme is now implemented, based on cooling loops corresponding to the length of a full-cell (107 m) and compatible with the LHC requirements. Performance and redundancy limitations are discussed with respect to the previous scheme and balanced against potential cost savings.
120691896
Precision heat inleak measurements on cryogenic components at 80 K, 4.2 K and 1.8 K
Abstract We have built and are operating a test bench for precision heat inleak measurements and thermal qualification of components for the superfluid helium cryostats of the CERN Large Hadron Collider (LHC) project. The bench features the three temperature levels used for heat interception in the LHC cryostats. The heat loads are measured using both calibrated thermal conductances (“heatmeters”) and standard boil-off methods. After validation of the measurement methods, we compare experimental results with thermal design calculations on a prototype magnet support post.
116930106
Performance of the twin-aperture dipole for the CERN LHC
The paper reports about the measurements performed on the Twin-Aperture Prototype Dipole (TAP) for the CERN Large Hadron Collider. This dipole was designed by CERN and built by European industry. A comprehensive programme for magnetic and cryogenic measurements is in progress at CEN, Saclay, in France. The measurement campaign includes studies of time dependent field effects and detailed measurements of the influence of excitation history on the. remanent field.
122472626
Recent results from Fermilab E687 on charm spectroscopy
Recent analyses of charm spectroscopy from Fermilab fixed target experiment 687 [1] are summarized. Emphasis is placed on the phenomenology of Cabibbo suppression in the meson sector. Such transitions have been observed in the semileptonic modes and hadronic modes. While the former transitions give us an opportunity to observe the weak current and the CKM matrix, a systematic comparison of the latter transitions allow us to study strong interaction effects, and possibly, light quark spectroscopy.
124018243
Demands in Refrigeration Capacity for the Large Hadron Collider
The capacity demands on the cryogenic installations for the Large Hadron Collider (LHC) at CERN have been recently updated [1]. Unlike the LEP energy upgrade using superconducting acceleration cavities LHC will require high power refrigeration at 1.9 K, as well as non-isothermal cooling at 4.5 K to 20 K and at 50 K to 75 K. This paper presents the assessment of cryogenic capacity that has to be supplied by the eight refrigerators for LHC in relation with the foreseen operating modes of the machine.