The Vertex Locator (VELO) is a silicon microstrip detector that surrounds the proton-proton interaction region in the LHCb experiment. The performance of the detector during the first years of its ...physics operation is reviewed. The system is operated in vacuum, uses a bi-phase CO sub(2) cooling system, and the sensors are moved to 7 mm from the LHC beam for physics data taking. The performance and stability of these characteristic features of the detector are described, and details of the material budget are given. The calibration of the timing and the data processing algorithms that are implemented in FPGAs are described. The system performance is fully characterised. The sensors have a signal to noise ratio of approximately 20 and a best hit resolution of 4 mu m is achieved at the optimal track angle. The typical detector occupancy for minimum bias events in standard operating conditions in 2011 is around 0.5%, and the detector has less than 1% of faulty strips. The proximity of the detector to the beam means that the inner regions of the n super(+)-on-n sensors have undergone space-charge sign inversion due to radiation damage. The VELO performance parameters that drive the experiment's physics sensitivity are also given. The track finding efficiency of the VELO is typically above 98% and the modules have been aligned to a precision of 1 mu m for translations in the plane transverse to the beam. A primary vertex resolution of 13 mu m in the transverse plane and 71 mu m along the beam axis is achieved for vertices with 25 tracks. An impact parameter resolution of less than 35 mu m is achieved for particles with transverse momentum greater than 1 GeV/c.
Electron spectroscopy with a diamond detector Bodie, C.S.; Lioliou, G.; Lefeuvre, G. ...
Applied radiation and isotopes,
February 2022, 2022-Feb, 2022-02-00, 20220201, Volume:
180
Journal Article
Peer reviewed
Open access
An electronic grade single crystal chemical vapour deposition diamond was investigated as a prototype high temperature spectroscopic electron (β- particle) detector for future space science ...instruments. The diamond detector was coupled to a custom-built charge-sensitive preamplifier of low noise. A 63Ni radioisotope source (endpoint energy 66 keV) was used to provide a spectrum of β- particles incident on the detector. The operating temperature of the detector/preamplifier assembly was controlled to allow its performance to be investigated between +100 °C and −20 °C, in 20 °C steps. Monte Carlo modelling was used to: a) calculate the β- particle spectrum incident on the detector; b) calculate the fraction of β- particle energy deposited into the detector; and c) predict the β- particle spectrum accumulated by the instrument. Comparison between the model and experimental data suggested that there was a 4.5 μm thick recombination region at the front of the detector. The spectrometer was demonstrated to be fully operable at temperatures, T, −20 °C ≤ T ≤ 80 °C; the results suggested that some form of polarisation phenomenon occurred in the detector at > 80 °C. This article presents the first report of an energy calibrated (≲ 50 keV) spectroscopic β- particle diamond detector.
•A proof-of-principle high temperature tolerant electron spectrometer is reported.•The spectrometer utilised a prototype chemical vapour deposition diamond detector.•Electrons from a63Ni radioisotope β− particle source detected spectroscopically.•The instrument operated successfully at temperatures ≤80 °C.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have ...been applied to an enlarged data sample from an exposure of 7.25×10(20) protons on target. A fit to neutrino oscillations yields values of |Δm(2)|=(2.32(-0.08)(+0.12))×10(-3) eV(2) for the atmospheric mass splitting and sin(2)(2θ)>0.90 (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.
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Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an ...exposure to the NuMI neutrino beam of 7.07×10(20) protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of 754 ± 28(stat) ± 37(syst) for oscillations among three active flavors. The fraction f(s) of disappearing ν(μ) that may transition to ν(s) is found to be less than 22% at the 90% C.L.
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We searched for a sidereal modulation in the MINOS far detector neutrino rate. Such a signal would be a consequence of Lorentz and CPT violation as described by the standard-model extension ...framework. It also would be the first detection of a perturbative effect to conventional neutrino mass oscillations. We found no evidence for this sidereal signature, and the upper limits placed on the magnitudes of the Lorentz and CPT violating coefficients describing the theory are an improvement by factors of 20-510 over the current best limits found by using the MINOS near detector.
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Single crystal CVD diamond has many desirable properties as a radiation detector; exceptional radiation hardness and physical hardness, chemical inertness, low Z (close to human tissue, good for ...dosimetry and transmission mode applications), wide bandgap (high temperature operation with low noise and solar blind), an intrinsic pathway to fast neutron detection through the super(12) C(n,alpha) super(9) Be reaction. This combination of radiation hardness, temperature tolerance and ability to detect mixed radiation types with a single sensor makes diamond particularly attractive as a detector material for harsh environments such as nuclear power station monitoring (fission and fusion) and oil well logging. Effective exploitation of these properties requires the development of a metallisation scheme to give contacts that remain stable over extended periods at elevated temperatures (up to 250degreesC in this instance). Due to the cost of the primary detector material, computational modelling is essential to best utilise the available processing methods for optimising sensor response through geometry and conversion media configurations and to fully interpret experimental data. Monte Carlo simulations of our diamond based sensor have been developed, using MCNP6 and FLUKA2011, assessing the sensor performance in terms of spectral response and overall efficiency as a function of the detector and converter geometry. Sensors with varying metallisation schemes for high temperature operation have been fabricated at Brunel University London and by Micron Semiconductor Limited. These sensors have been tested under a varied set of conditions including irradiation with fast neutrons and alpha particles at high temperatures. The presented study indicates that viable metallisation schemes for high temperature contacts have been successfully developed and the modelling results, supported by preliminary experimental data from partners, indicate that the simulations provide a reasonable representation of detector response.
This Letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ν(μ) production, accumulating an ...exposure of 1.71 × 10²⁰ protons on target. In the Far Detector, 97 charged current ν(μ) events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at 6.3σ. The best fit to oscillation yields |Δm²| = 3.36(-0.40)(+0.46)(stat) ± 0.06(syst) × 10⁻³ eV², sin²(2θ) = 0.86(-0.12)(+0.11)(stat) ± 0.01(syst). The MINOS ν(μ) and ν(μ) measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters.
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From SNO to SNO+, upgrading a neutrino experiment Lefeuvre, G.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Volume:
718
Journal Article
Peer reviewed
SNO+ is a multi-purpose neutrino experiment in construction in SNOLAB, Canada, the deepest underground laboratory. It succeeds the SNO experiment, replacing heavy water by liquid scintillator and ...thus lowering the sensitivity to a lower energy threshold. SNO+ will study low energy solar neutrinos, including those from the pep and CNO cycles. Loading the liquid scintillator with almost a ton of Neodymium will then enable the search for neutrinoless double beta decay. SNO+ also aims at detecting reactor, geo- and possibly supernova neutrinos. All the components of the detector must reach and maintain a very high level of radiopurity. I will discuss in detail the calibration programme that has been developed for SNO+ and that must at all time keep in mind these radiopurity requirements.
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9.
Silicon detectors for the sLHC Affolder, A.; Allport, P.P.; Bates, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Volume:
658, Issue:
1
Journal Article
Peer reviewed
In current particle physics experiments, silicon strip detectors are widely used as part of the inner tracking layers. A foreseeable large-scale application for such detectors consists of the ...luminosity upgrade of the Large Hadron Collider (LHC), the super-LHC or sLHC, where silicon detectors with extreme radiation hardness are required. The mission statement of the CERN RD50 Collaboration is the development of radiation-hard semiconductor devices for very high luminosity colliders. As a consequence, the aim of the R&D programme presented in this article is to develop silicon particle detectors able to operate at sLHC conditions. Research has progressed in different areas, such as defect characterisation, defect engineering and full detector systems. Recent results from these areas will be presented. This includes in particular an improved understanding of the macroscopic changes of the effective doping concentration based on identification of the individual microscopic defects, results from irradiation with a mix of different particle types as expected for the sLHC, and the observation of charge multiplication effects in heavily irradiated detectors at very high bias voltages.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The LHCb RICH1 detector uses hybrid photon detectors (HPDs) as its optical sensors. A calibration system has been constructed to provide corrections for distortions that are primarily due to external ...magnetic fields. We describe here the system design, construction, operation and performance.
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