110998320
Determination of the Tc distribution for 1000 Transition Edge Sensors
The ZIP detectors deployed in the CDMS II experiment utilize phonon sensors comprising W Transition Edge Sensors (TESs). In order to ensure uniform collection of the athermal phonon signal the TESs are dispersed uniformly on one side of a 1 cm thick, 3 inch diameter, disk. Each quadrant contains 1036 TESs connected in parallel to one series-array SQUID amplifier. The initial superconducting transition temperatures of these TESs tend to be too high for our requirements, and substantial gradients make the operation of the detectors difficult. Hence our implementation of Fe-56 ion implantation, as reported at the previous LTD meeting, to reduce in a controlled manner the transition temperature. However, the successful implementation of this ion-implantation scheme requires accurate knowledge of the initial transition temperature of each TES in a given quadrant. We report on our approaches and techniques employed to address the issue of determining the initial Tc distribution.
118705215
The Cryogenic Dark Matter Search and Background Rejection with Event Position Information
110284812
SVD-BASED METHOD FOR MEASUREMENT OF BEAM PARAMETERS AND FLAG RESOLUTION *
In NSLS II booster to storage ring transport line, the typical beam size in vertical plane is ~60 �� m, which requires very high flag resolution to get good beam parameters measurement. This paper describes a new SVD-based method to measure transverse beam parameters and flag resolution simultaneously with double quads scan. Implementation simulations of the proposed method are performed for a dispersion free region in the NSLS-II booster to storage ring transport line. With this method, it breaks the limitation of beam parameters measurement accuracy due to the flag resolution.
119169539
Elliptic flow in the Gaussian model of eccentricity fluctuations
Abstract We discuss a specific model of elliptic flow fluctuations due to Gaussian fluctuations in the initial spatial x and y eccentricity components { 〈 ( σ y 2 − σ x 2 ) / ( σ x 2 + σ y 2 ) 〉 , 〈 2 σ x y / ( σ x 2 + σ y 2 ) 〉 } . We find that in this model v 2 { 4 } , elliptic flow determined from 4-particle cumulants, exactly equals the average flow value in the reaction plane coordinate system, 〈 v RP 〉 , the relation which, in an approximate form, was found earlier by Bhalerao and Ollitrault in a more general analysis, but under the same assumption that v 2 is proportional to the initial system eccentricity. We further show that in the Gaussian model all higher order cumulants are equal to v 2 { 4 } . Analysis of the distribution in the magnitude of the flow vector, the Q -distribution, reveals that it is totally defined by two parameters, v 2 { 2 } , the flow from 2-particle cumulants, and v 2 { 4 } , thus providing equivalent information compared to the method of cumulants. The flow obtained from the Q -distribution is again v 2 { 4 } = 〈 v RP 〉 .
14324888
Incident-energy and system-size dependence of directed flow
We present STAR's measurements of directed flow for charged hadrons in Au+Au and Cu+Cu collisions at GeV and 62.4 GeV, as a function of pseudorapidity, transverse momentum and centrality. We find that directed flow depends on the incident energy, but not on the system size. We extend the validity of limiting fragmentation hypothesis to different collision systems.
110815008
Implementation of a DC Bump at the Storage Ring Injection Straight Section
The NSLS II beam injection works with a DC septum, a pulsed septum and four fast kicker magnets. The kicker power supplies each produce a two revolution period pulsed field, 5.2 {micro}s half sine waveform, using {approx}5kA drive voltage. The corresponding close orbit bump amplitude is {approx}15mm. It is desired that the bump is transparent to the users for top-off injection. However, high voltage and short pulse power supplies have challenges to maintain pulse-to-pulse stability and magnet-to-magnet reproducibility. To minimize these issues, we propose implementing a DC local bump on top of the fast bump to reduce the fast kicker strength by a factor of 2/3. This bump uses two storage ring corrector magnets plus one additional magnet at the septum to create a local bump. Additionally, these magnets could provide a DC bump to simulate the septum position effects on the store beam lifetime. This paper presents the detail design of this DC injection bump and related beam dynamics.
119770548
ION CHANNELING STUDY OF RADIATION INDUCED DEFECTS IN A BENT SILICON CRYSTAL
Abstract High energy proton channeling (12–120 GeV) and low energy helium ion channeling (1.5–4 MeV) have been used to study the effects of radiation damage induced in silicon by high energy (400 GeV) proton irradiation. It is shown that radiation fluence up to 1017/cm2 does not preclude deflection of high energy charged particle beams in elastically bent silicon crystals. Evidence of macroscopic segregation of residual defects in the strain field of a deformed crystal is demonstrated.