The extended TeV gamma-ray source ARGO J2031+4157 (or MGRO J2031+41) is positionally consistent with the Cygnus Cocoon discovered by Fermi-LAT at GeV energies in the Cygnus superbubble. Reanalyzing ...the ARGO-YBJ data collected from 2007 November to 2013 January, the angular extension and energy spectrum of ARGO J2031+4157 are evaluated. After subtracting the contribution of the overlapping TeV sources, the ARGO-YBJ excess map is fitted with a two-dimensional Gaussian function in a square region of 10degrees x 10degrees, finding a source extension sigma sub(ext)= 1degrees.8 + or - 0degrees.5. The observed differential energy spectrum is dN/dE = (2.5 + or - 0.4) x 10 super(-11) (E/1 TeV) super(-2.6+ or -0.3) photons cm super(-2) s super(-1) TeV super(-1), in the energy range 0.2-10 TeV. The angular extension is consistent with that of the Cygnus Cocoon as measured by Fermi-LAT and the spectrum also shows a good connection with the one measured in the 1-100 GeV energy range. These features suggest to identify ARGO J2031+4157 as the counterpart of the Cygnus Cocoon at TeV energies. The Cygnus Cocoon, located in the star-forming region of Cygnus X, is interpreted as a cocoon of freshly accelerated cosmic rays related to the Cygnus superbubble. The spectral similarity with supernova remnants (SNRs) indicates that the particle acceleration inside a superbubble is similar to that in an SNR. The spectral measurements from 1 GeV to 10 TeV allows for the first time to determine the possible spectrum slope of the underlying particle distribution. A hadronic model is adopted to explain the spectral energy distribution.
Abstract
In this paper we provide a detailed technical description of the Front-End (FE) electronics for the liquid Argon instrumentation of the LEGEND-200 experiment, searching for the very rare, ...hypothetical neutrinoless double β decay process at the Italian Laboratori Nazionali del Gran Sasso. The design stems from the need to read out the silicon photo-multiplier response to the scintillation light in the liquid Argon with excellent single-photon resolution. The FE electronics is required to be placed far from the detectors to meet the experiment's radio-purity constraints. This constraint represents a challenge for a high signal-to-noise ratio. We address how this could be achieved in a stable way. The system was installed in July 2021 and has been commissioned with the rest of LEGEND-200, proving we could attain a very low overall level of
electrical noise of 250 μV peak-to-peak.
The Astrophysical Radiation with Ground-based Observatory at Yang Ba Jing (ARGO-YBJ) detector is an extensive air shower array that has been used to monitor the northern gamma -ray sky at energies ...above 0.3 TeV from 2007 November to 2013 January. In this paper, we present the results of a sky survey in the declination band from -10degrees to 70degrees, using data recorded over the past five years. With an integrated sensitivity ranging from 0.24 to ~1 Crab units depending on the declination, six sources have been detected with a statistical significance greater than five standard deviations. Several excesses are also reported as potential gamma -ray emitters. The features of each source are presented and discussed. Additionally, 95% confidence level upper limits of the flux from the investigated sky region are shown. Specific upper limits for 663 GeV gamma -ray active galactic nuclei inside the ARGO-YBJ field of view are reported. The effect of the absorption of gamma -rays due to the interaction with extragalactic background light is estimated.
Based on a sample of 300 million KS mesons produced in ϕ→KLKS decays recorded by the KLOE experiment at the DAΦNE e+e− collider we have measured the branching fraction for the decay KS→πμν. The KS ...mesons are identified by the interaction of KL mesons in the detector. The KS→πμν decays are selected by a boosted decision tree built with kinematic variables and by a time-of-flight measurement. Signal efficiencies are evaluated with data control samples of KL→πμν decays. A fit to the reconstructed muon mass distribution finds 7223±180 signal events. Normalising to the KS→π+π− decay events the result for the branching fraction is B(KS→πμν)=(4.56±0.11stat±0.17syst)×10−4. It is the first measurement of this decay mode and the result allows an independent determination of |Vus| and a test of the lepton-flavour universality.
The ARGO-YBJ air shower detector monitored the Crab Nebula gamma-ray emission from 2007 November to 2013 February. The integrated signal, consisting of ~3.3 x 10 super(5) events, reached the ...statistical significance of 21.1 standard deviations. The obtained energy spectrum in the energy range 0.3-20 TeV can be described by a power law function dN/dE = I sub(0) (E/2 TeV) super(-alpha), with a flux normalization I sub(0) = (5.2 + or - 0.2) x 10 super(-12) photons cm super(-2) s super(-1) TeV super(-1) and alpha = 2.63 + or - 0.05, corresponding to an integrated flux above 1 TeV of 1.97 x 10 super(-11) photons cm super(-2) s super(-1). The systematic error is estimated to be less than 30% for the flux normalization and 0.06 for the spectral index. Assuming a power law spectrum with an exponential cutoff dN/dE = I sub(0) (E/2 TeV) super(-alpha) exp (-E/E sub(cut)), the lower limit of the cutoff energy E sub(cut) is 12 TeV, at 90% confidence level. Our extended data set allows the study of the TeV emission over long timescales. Over five years, the light curve of the Crab Nebula in 200-day bins is compatible with a steady emission with a probability of 7.3 x 10 super(-2). A correlated analysis with Fermi-LAT data over ~4.5 yr using the light curves of the two experiments gives a Pearson correlation coefficient r = 0.56 + or - 0.22. Concerning flux variations on timescales of days, a "blind" search for flares with a duration of 1-15 days gives no excess with a significance higher than four standard deviations. The average rate measured by ARGO-YBJ during the three most powerful flares detected by Fermi-LAT is 205 + or - 91 photons day super(-1), consistent with the average value of 137 + or - 10 day super(-1).
A
bstract
Based on an integrated luminosity of 1.61 fb
−
1
e
+
e
−
collision data collected with the KLOE detector at DAΦNE, the Frascati
ϕ
-factory, a search for the
P
- and
CP
-violating decay
η → ...π
+
π
−
has been performed. Radiative
ϕ → ηγ
decay is exploited to access the
η
mesons. No signal is observed in the
π
+
π
−
invariant mass spectrum, and the upper limit on the branching fraction at 90% confidence level is determined to be ℬ(
η → π
+
π
−
)
<
4
.
9
×
10
−
6
, which is approximately three times smaller than the previous KLOE result. From the combination of these two measurements we get ℬ(
η → π
+
π
−
)
<
4
.
4
×
10
−
6
at 90% confidence level.
The Belle II experiment will operate at the SuperKEKB e+ e- collider, designed to reach a top luminosity of 8 × 10 35 at the Υ(4s) resonance. The high background environment of the accelerator po ses ...serious challenges to the design of the detector. In particular, the Belle II collaboration is developing an ambitious upgrade program that involves the forward electromagnetic calorimeter. We will use pure CsI crystals, since they have less scintillation time but unfortunately much lower light yield. The electromagnetic calorimeter upgrade is subject to the same detector constraints as the first design; an intense research and development program on photon-detectors and front-end electronics has been initiated by the Italian collaboration. Our preliminary results show that a readout chain using avalanche photodiodes (APDs) to match the detector constraints and a dedicated front-end card for the readout meet the Belle II collaboration requirements. In this paper, we will show the experimental setup and detail the main characteristics of the read-out and power distribution system since the front-end card hosts both a low noise preamplifier and a power regulator to set the single APD bias voltage. The main HV module has been developed for this purpose to deliver a low noise power distribution to the front-end cards. All the relevant parameters of the front-end system can be set and monitored via Ethernet using the Experimental Physics and Industrial Control System. Slow control and monitoring functions in Belle II are performed by a dedicated hardware. The platform has been designed as an uP-based service-oriented platform, capable to offer an integrated solution for all the needs of data acquisition, analysis, and network functions.
The Data Acquisition System (DAQ) and the Front-End electronics for an array of Kinetic Inductance Detectors (KIDs) are described. KIDs are superconductive detectors, in which electrons are organized ...in Cooper pairs. Any incident radiation could break a pair generating a couple of quasi-particles that increase the inductance of the detector. The DAQ system we developed is a hardware software co-design, based on state machines and on a microprocessor embedded into an FPGA. A commercial DAC ADC board is used to interface the FPGA to the array of KIDs. The DAQ system generates a Stimulus signal suitable for an array of up to 128 KIDs. Such signal is up-mixed with a 3 GHz carrier wave and it then excites the KIDs array. The read-out signal from the detector is down-mixed with respect to the 3 GHz sine wave and recovered Stimulus is read back by the ADC device. The microprocessor stores read out data via a PCI express bus (PCIe) into an external disk. It also computes the Fast Fourier Transform of the acquired read out signal: this allows extrapolating which KID interacted and the energy of the impinging radiation. Simulations and tests have been performed successfully and experimental results are presented.
We report the observation of TeV gamma -rays from the Cygnus region using the ARGO-YBJ data collected from 2007 November to 2011 August. Several TeV sources are located in this region including the ...two bright extended MGRO J2019+37 and MGRO J2031+41. According to the Milagro data set, at 20 TeV MGRO J2019+37 is the most significant source apart from the Crab Nebula. No signal from MGRO J2019+37 is detected by the ARGO-YBJ experiment, and the derived flux upper limits at the 90% confidence level for all the events above 600 GeV with medium energy of 3 TeV are lower than the Milagro flux, implying that the source might be variable and hard to be identified as a pulsar wind nebula. The only statistically significant (6.4 standard deviations) gamma -ray signal is found from MGRO J2031+41, with a flux consistent with the measurement by Milagro.
A LYSO calorimeter for the SuperB factory Eigen, G.; Zhou, Z.; Chao, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Letnik:
718
Journal Article
Recenzirano
Odprti dostop
The SuperB project is an asymmetric e+e− accelerator of 1036cm−2s−1 design luminosity, capable of collecting a data sample of 50–75ab−1 in five years running. The SuperB electromagnetic calorimeter ...(EMC) provides energy and direction measurement of photons and electrons, and is used for identification of electrons versus other charged particles. In particular we present its design, geometry study and related simulations, as well as R&D on LYSO crystals and developments on readout electronics. A matrix of 25 crystals has been tested at the Beam Test Facility of Frascati (BTF) in May 2011 at energies between 200MeV and 500MeV. Results from this test are presented.
PDF
