111339244
Bonded wafer substrates for integrated detector arrays
Bonded wafer substrates that are optimized for integrating high-energy-particle silicon detector arrays with their readout electronics have been fabricated. The detectors are processed in the handle wafer, which is a 300- mu m-thick, high-resistivity, silicon wafer. This wafer is bonded to a primary wafer using a low-temperature process that does not affect the detector material. The support electronics are processed in the remnant of the primary wafer, which is a submicron-thick silicon film formed by a bond-and-etchback procedure. These two materials are isolated from each other by a radiation-hardened dielectric film. The integration process is based on a low-temperature, radiation-hardened VLSI CMOS process that is also shown not to seriously affect the detector material. >
49389105
DESIGN OF MAIN RING DIPOLE POWER SUPPLY FOR HIRFL-CSR *
This paper introduces the main circuit topologic, control method and double reference setting system of a dipole power supply which is the pivotal device of the HIRFL-CSR (Heavy Ion Research Facility in LanzhouCooling Storage Ring). The power supply works at the pulse mode, with the peak output power of 3.15MW (3000A, 1045V). To fulfil difficult requirements especially for the tracking error, which is needed less than 300ppm, a special topologic is adopted. The power supply has two parts: SCR rectifier provides the most energy and PWM converter provides correcting current and perfect reaction for tracking current setting. Now the dipole power supply is performing well during the CSR commissioning, with the perfect tracking error, well longtime stability and low ripple current. INTRODUCTION OF THE POWER SUPPLY The power supply is a pivotal device of HIRFL-CSR (Heavy Ion Research Facility in Lanzhou-Cooling Storage Ring), and it is a synchronized one. This synchronized power supply’s output current must track the setting as Fig. 1. Figure 1: Plots of current and ideal voltage. In Fig. 1, the output voltage only happens at the ideal state. For heavy iron beam acceleration, the most important requirements on the power supply are listed below: Peak output power 3.15MW (3000A/1045V) Tracking error less than 200ppm Current stability better than 3×10 This power supply works at two modes, one is the DC output mode and the other is Pulse output mode, in most cases the control system’s parameters are different at the two modes. DIPOLE POWER SUPPLY’S SCHEMATIC DIAGRAM To fulfil these stringent requirements as mentioned above, our dipole power supply has two parts: SCR rectifier and switching mode DC converter. Fig. 2 shows the schematic diagram of the power supply. In part one, we use 12 SCRs and connect them into two serial normal 3-phases SCR rectifiers. The transformer’s input comes from 10KV power line, and the second side output voltage is 495V.This part provides the most output power (95%). IGBT is adopted in part two, which consists of 4 DC converters. Each DC converter uses a full-Bridge topologic and be connected in serial mode to supply the high-voltage output capability. As we all know, the traditional SCR rectifier has advantages of high power output ability, high credibility and low-cost. But the SCR rectifier also has disadvantage of slow response in synchronized power supply. For the reason mentioned above, the switching mode converter is used to improve the fast-response ability. The very high switching frequency of IGBT makes it easy to control the power supply’s output with a small tracking error. But the switching mode rectifier is of high-cost. In our power supply, we use the advantages of the two modes. It means that the SCR rectifier provides the most output power and the switching mode rectifier provides the fast-response ability for current tracking. There is a balance between the output powers of the two parts. In this power supply, the switching part can supply maximum current up to 200A, but in most cases this part’s maximum output is less than 200A. The maximum output is controlled by a constant input, which is introduced in the following part of this paper.
125771026
Letter of intent for the study of CP violation and heavy flavor physics at PEP-II
110247079
Charge division read-out in a 1.8-m-long wire chamber
This paper reports on the design and the test results of a charge division electronic read-out system for a charged particle proportional wire detector. Electronic calibration and probable error analysis of the system are also discussed. Position resolution for the system has been measured to be 4.8-mm FWHM on a wire of 1.8-m length (0.26%, relative). >
14588649
Production of e, mu and tau pairs in untagged two-photon collisions at LEP
The two-photon collision reaction e+e- --> e+e-l+l- has been studied at root(s) ~ 91 GeV using the L3 detector at LEP for l = e, muon , tau. We have analysed untagged configurations where the two photons are quasi-real. Good agreement is found between our measurements and the order alpha**4 QED expectation.
16335111
X-RAY STAR CLUSTERS IN THE CARINA COMPLEX
The distribution of young stars found in the Chandra Carina Complex Project (CCCP) is examined for clustering structure. X-ray surveys are advantageous for identifying young stellar populations compared to optical and infrared surveys in suffering less contamination from nebular emission and Galactic field stars. The analysis is based on smoothed maps of a spatially complete subsample of ~3000 brighter X-ray sources classified as Carina members and ~10,000 stars from the full CCCP sample. The principal known clusters are recovered, and some additional smaller groups are identified. No rich embedded clusters are present, although a number of sparse groups are found. The CCCP reveals considerable complexity in clustering properties. The Trumpler 14 and 15 clusters have rich stellar populations in unimodal, centrally concentrated structures several parsecs across. Non-spherical internal structure is seen, and large-scale low surface density distributions surround these rich clusters. Trumpler 16, in contrast, is comprised of several smaller clusters within a circular boundary. Collinder 228 is a third type of cluster which extends over tens of parsecs with many sparse compact groups likely arising from triggered star formation processes. A widely dispersed, but highly populous, distribution of X-ray stars across the ~50 pc CCCP mosaic supports a model of past generations of star formation in the region. Collinder 234, a group of massive stars without an associated cluster of pre-main-sequence stars, may be part of this dispersed population.
23658132
First look at the beam test results of the FPIX2 readout chip for the BTeV silicon pixel detector
High energy and nuclear physics experiments need tracking devices with increasing spatial precision and readout speed in the face of ever-higher track densities and increased radiation environments. The new generation of hybrid pixel detectors (arrays of silicon diodes bump bonded to arrays of front-end electronic cells) is the technology able to meet these challenges. We report the first results of the BTeV silicon pixel detector beam test carried out at Fermilab in summer 2004. Tests were performed using a 120 GeV/c proton beam incident on a 6 plane pixel detector telescope. The last prototype developed for the BTeV experiment (FPIX2) is tested in the middle of the telescope. There is no external trigger, and events were built using the time-stamp information provided by the readout chips
8085635
Beam test results of the BTeV silicon pixel detector
We report the main results of the BTeV silicon pixel detector beam test carried out at Fermilab during the fixed target run 1999-2000. The tests were performed using a 227 GeV/c pion beam incident on a 6 plane silicon microstrip telescope. Several single-chip silicon pixel planes were placed in the middle of the apparatus. The pixel detector spatial resolution has been studied as a function of track inclination and the number of ADC bits. The effect of an applied external magnetic field was also studied.
119252933
Competition between excitonic gap generation and disorder scattering in graphene
We study the disorder effect on the excitonic gap generation caused by strong Coulomb interaction in graphene. By solving the self-consistently coupled equations of dynamical fermion gap m and disorder scattering rate Γ, we have found a critical line on the plane of interaction strength λ and disorder strength g. The phase diagram is divided into two regions: in the region with large λ and small g, m≠0 and Γ=0; in the other region, m=0 and Γ≠0 for nonzero g. In particular, there is no coexistence of finite fermion gap and finite scattering rate. These results imply a strong competition between excitonic gap generation and disorder scattering. This conclusion does not change when an additional contact four-fermion interaction is included. For sufficiently large λ, the growing disorder may drive a quantum phase transition from an excitonic insulator to a metal.