The High Altitude Water Cherenkov observatory (HAWC) is an air shower array devised for TeV gamma-ray astronomy. HAWC is located at an altitude of 4100 m a.s.l. in Sierra Negra, Mexico. HAWC consists ...of 300 Water Cherenkov Detectors, each instrumented with 4 photomultiplier tubes (PMTs). HAWC re-uses the Front-End Boards from the Milagro experiment to receive the PMT signals. These boards are used in combination with Time to Digital Converters (TDCs) to record the time and the amount of light in each PMT hit (light flash). A set of VME TDC modules (128 channels each) is operated in a continuous (dead time free) mode. The TDCs are read out via the VME bus by Single-Board Computers (SBCs), which in turn are connected to a gigabit Ethernet network. The complete system produces ≈500 MB/s of raw data. A high-throughput data processing system has been designed and built to enable real-time data analysis. The system relies on off-the-shelf hardware components, an open-source software technology for data transfers (ZeroMQ) and a custom software framework for data analysis (AERIE). Multiple trigger and reconstruction algorithms can be combined and run on blocks of data in a parallel fashion, producing a set of output data streams which can be analyzed in real time with minimal latency (<5 s). This paper provides an overview of the hardware set-up and an in-depth description of the software design, covering both the TDC data acquisition system and the real-time data processing system. The performance of these systems is also discussed.
A muon storage ring for the g-2 experiment at Brookhaven National Laboratory will have a DC superconducting inflector magnet for injection of the muon beam. This inflector locally bucks out the 1.45 ...tesla storage ring dipole field, so that the muon beam enters the ring tangentially as close as possible to the equilibrium orbit. The g-2 experiment requires the knowledge of the magnetic field over the muon orbits to a precision of 0.1 ppm. The inflector has nested dipole coils of opposite polarity so that it cancels its external magnetic flux and generates very little stray field. Nevertheless the residual field would affect the homogeneity of the storage ring magnetic field. A method of using a multilayer superconducting (SC) composite sheet surrounding the inflector to further reduce the fringe field has been proposed. This sheet should prevent the stray field due to the inflector from affecting the field quality of the muon storage region. In developing this new type of air-core septum magnet, a shortened SC prototype inflector was built in Japan at KEK. It has been used for testing the superconducting performance (in KEK, BNL) and the fringe flux shielding (in BNL). Some of the test results are presented.< >
Spectroscopy of the 1S-2S energy splitting in muonium Schwarz, W.; Baird, P.E.G.; Barr, J.R.M. ...
IEEE transactions on instrumentation and measurement,
04/1995, Letnik:
44, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
A new measurement of the 1/sup 2/S/sub 1/2/-2/sup 2/5/sub 1/2/ energy splitting in muonium (/spl mu//sup +/e/sup -/) by Doppler-free two-photon laser spectroscopy yields a value of 2 455 529 002 (33) ...(46) MHz, where the 33 MHz error arises from statistics and the 46 MHz uncertainty is due to systematic line shifts. The experiment agrees with quantum electrodynamics theory within two standard deviations. The mass of the positive muon can be derived as 105.65880 (29) (43) MeV/c/sup 2/ from the measured muonium-hydrogen and muonium-deuterium 1S-2S isotope shifts. The measurement may alternatively be interpreted as a test of the equality of the electric charges of muon and electron with a precision of 1.4 (1.2) l0{-8}.< >
A muon g-2 experiment (E821) at the AGS requires knowledge of the magnetic field over muon orbits at the level of 0.1 ppm. The superconducting inflector involves a double cosine theta winding; this ...design approximately cancels its fringe field. Nevertheless its residual field would effect the homogeneity of the storage ring magnetic field. A method of using a superconducting sheet surrounding the inflector to further reduce the fringe field was proposed by one of the authors, W. Meng. An experimental program to explore this technique is described. Part of the test results are presented.< >
VAMOS1VAMOS is an acronym for: Verification and Assessment Measuring of Observatory Subsystem.1 was a prototype detector built in 2011 at an altitude of 4100m a.s.l. in the state of Puebla, Mexico. ...The aim of VAMOS was to finalize the design, construction techniques and data acquisition system of the HAWC observatory. HAWC is an air-shower array currently under construction at the same site of VAMOS with the purpose to study the TeV sky. The VAMOS setup included six water Cherenkov detectors and two different data acquisition systems. It was in operation between October 2011 and May 2012 with an average live time of 30%. Besides the scientific verification purposes, the eight months of data were used to obtain the results presented in this paper: the detector response to the Forbush decrease of March 2012, and the analysis of possible emission, at energies above 30GeV, for long gamma-ray bursts GRB111016B and GRB120328B.
To search for spontaneous conversion of muonium to antimuonium with very low background, a new signature was implemented that required the coincident detection of the decay products of the ...antimuonium atom, the energetic {ital e}{sup {minus}} and the atomic {ital e}{sup +}. No conversion events were seen, which sets an improved upper limit of 6.5{times}10{sup {minus}7} (90% C.L.) on the conversion probability. The corresponding limit on the coupling constant, using a {ital V}{minus}{ital A} form for the conversion Hamiltonian, is {ital G}{sub {ital M}{ital {bar M}}}{lt}0.16{ital G}{sub {ital F}} (90% C.L.), where {ital G}{sub {ital F}} is the Fermi coupling constant.
The superconducting inflector for the BNL g-2 experiment Yamamoto, A; Makida, Y; Tanaka, K ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2002, Letnik:
491, Številka:
1-2
Journal Article
Recenzirano
The muon g-2 experiment at Brookhaven National Laboratory (BNL) has the goal of determining the muon anomalous magnetic moment, aμ(=(g-2)/2), to the very high precision of 0.35 parts per million and ...thus requires a storage ring magnet with great stability and homogeneity. A super-ferric storage ring has been constructed in which the field is to be known to 0.1ppm. In addition, a new type of air core superconducting inflector has been developed and constructed, which successfully serves as the injection magnet. The injection magnet cancels the storage ring field, 1.5T, seen by the entering muon beam very close to the storage ring aperture. At the same time, it gives negligible influence to the knowledge of the uniform main magnetic field in the muon storage region located at just 23mm away from the beam channel. This was accomplished using a new double cosine theta design for the magnetic field which traps most of the return field, and then surrounding the magnet with a special superconducting sheet which traps the remaining return field. The magnet is operated using a warm-to-cold cryogenic cycle which avoids affecting the precision field of the storage ring. This article describes the design, research development, fabrication process, and final performance of this new type of superconducting magnet.
The g-2 experiment dipole consists of a single 48 turn, 15.1 meter diameter outer solenoid and a pair of 24 turn inner solenoids, 13.4 meters in diameter. The inner solenoids are hooked in series and ...are run at a polarity that is opposite that of the outer solenoid, thus creating a dipole field in the space between the inner and outer solenoids. The dipole flux is returned by a C shaped continuous iron yoke. The superconducting solenoid coils are closely coupled to the solenoid mandrels and as such are subject to quench back. This report presents the results of various tests on the g-2 magnet system operating within its iron return yoke. These tests include quench back time constant measurements for the inner and outer solenoids and measurements of the response of the two-phase forced cooled helium cryogenic system to magnet quenches. The overall effectiveness of the g-2 magnet quench protection system was measured.
PDF
