Elastic electron-proton scattering (e-p) and the spectroscopy of hydrogen atoms are the two methods traditionally used to determine the proton charge radius, r
. In 2010, a new method using muonic ...hydrogen atoms
found a substantial discrepancy compared with previous results
, which became known as the 'proton radius puzzle'. Despite experimental and theoretical efforts, the puzzle remains unresolved. In fact, there is a discrepancy between the two most recent spectroscopic measurements conducted on ordinary hydrogen
. Here we report on the proton charge radius experiment at Jefferson Laboratory (PRad), a high-precision e-p experiment that was established after the discrepancy was identified. We used a magnetic-spectrometer-free method along with a windowless hydrogen gas target, which overcame several limitations of previous e-p experiments and enabled measurements at very small forward-scattering angles. Our result, r
= 0.831 ± 0.007
± 0.012
femtometres, is smaller than the most recent high-precision e-p measurement
and 2.7 standard deviations smaller than the average of all e-p experimental results
. The smaller r
we have now measured supports the value found by two previous muonic hydrogen experiments
. In addition, our finding agrees with the revised value (announced in 2019) for the Rydberg constant
-one of the most accurately evaluated fundamental constants in physics.
Abstract
The PICOSEC Micromegas precise timing detector is based on a Cherenkov radiator coupled to a photocathode operating in a semi-transparent mode and a Micromegas amplification structure. The ...first proof of concept single-channel prototype was able to achieve a time resolution below 25 ps. One of the crucial aspects in the development of precise timing gaseous detectors applicable in high-energy physics experiments is a modular design that enables large area coverage. The first 19-channel multi-pad prototype with an active area of approximately 10 cm
2
suffered from degraded timing resolution due to the non-uniformity of the preamplification gap thickness. A new 100 cm
2
detector module with 100 channels based on a rigid hybrid ceramic/FR4 Micromegas board for improved drift gap uniformity was developed. Initial measurements with 80 GeV/c muons showed improvements in timing response over the measured pads and a time resolution below 25 ps. More recent measurements with a thinner drift gap detector module and newly developed RF pulse amplifiers show that the pad centre resolution can be enhanced to the level of 17 ps. This work will present the development of the detector from structural simulations, design, and beam test commissioning with a focus on the timing performance of a thinner drift gap detector module in combination with new electronics using an automated timing scan method.
GEM based detector for future upgrade of the CMS forward muon system Abbaneo, D.; Armagnaud, C.; Abbrescia, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2013, Letnik:
718
Journal Article
Recenzirano
In view of an upgrade of the CMS experiment, the GEM for CMS collaboration is performing feasibility studies on employing Triple-GEM detectors for the high-η region (1.6–2.4) of the CMS endcaps. A ...detailed review of the development and characterization of the CMS full-size prototype baseline detector will be presented. GEMs have excellent spatial and time resolution, high rate capability and radiation hardness, they are an appealing option for simultaneously enhancing muon tracking and triggering capabilities in the high-η region. The GEM for CMS collaboration has studied the performance of small and full-size prototype detectors during several test beam campaigns in order to validate new technologies and techniques in view of a mass production for CMS experiment. Results from measurements with x-rays and from test beam campaigns at the CERN SPS will be shown from both small and large prototypes.
Upgrades of the LHC detectors target significantly higher event rates and higher bandwidth over point-to-point links. The Data, Trigger, Clock and Control (DTCC) is a new custom link protocol for ...data and control streams over different physical media, as copper or optical fibre. The DTCC link is implemented over 8b10b encoding. A version of the DTCC link over standard Category 6 cables is planned to be used with ALICE EMCal Calorimeters after its LSI upgrade with a significant increase of the readout rate 1.
Performance of modular ring imaging Cherenkov detector for particle identification Sharma, D.; Barion, L.; Contalbrigo, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
April 2024, 2024-04-00, 2024-04-01, Letnik:
1061, Številka:
C
Journal Article
Recenzirano
A compact modular ring imaging Cherenkov (mRICH) detector has been developed to provide K/π separation over a momentum coverage of 2 to 10 GeV/c, and an e/π separation of up to 2.5 GeV/c within the ...Electron-Ion Collider Generic R&D Consortium (i.e., eRD14 Collaboration). The mRICH detector consists of an aerogel block, a Fresnel lens, a flat-mirror set, and a photosensor plane. In September 2021, an mRICH beam-test was carried out at Jefferson Laboratory (JLab). In this paper, results from JLab beam test will be presented together with future plans for mRICH R&D activities.
A new Transition Radiation detector based on GEM technology Barbosa, F.; Fenker, H.; Furletov, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2019, Letnik:
942, Številka:
C
Journal Article
Recenzirano
Odprti dostop
Transition Radiation Detectors (TRD) have the attractive feature of separating particles by their gamma factor. Classical TRDs are based on Multi-Wire Proportional Chambers (MWPC) or straw tubes, ...using a Xenon based gas mixture to efficiently absorb transition radiation photons. These detectors operate well in experiments with relatively low particle multiplicity. The performance of MWPC-TRD in experiments with luminosity of order 1034cm2s−1 and above, is significantly deteriorated due to the high particle multiplicity and channel occupancy. Replacing MWPC or straw tubes with a high granularity Micro Pattern Gas Detectors (MPGD) like Gas Electron Multipliers (GEMs), could improve the performance of the TRD. In addition, GEM technology allows one to combine a tracker with TRD identification (GEM-TRD/T). This report presents a new TRD development based on GEM technology for the future Electron Ion Collider (EIC). The first beam test was performed at Jefferson Lab (Hall-D) using 3–6 GeV electrons. A GEM-TRD/T module has been exposed to electrons with and without a fiber radiator. First results of test beam measurements and comparison with Geant4 Monte Carlo are presented in this article.
•New development of a transition radiation detector based on GEM technology.•The first results of beam test measurements and comparison with Geant4 Monte Carlo.•Neural network algorithms for extracting the electron/pion rejection power.
Muon tomography (MT) based on the measurement of multiple scattering of atmospheric cosmic ray muons traversing shipping containers is a promising candidate for identifying threatening high-Z ...materials. Since position-sensitive detectors with high spatial resolution should be particularly suited for tracking muons in a MT application, we propose to use compact micro-pattern gas detectors, such as gas electron multipliers (GEMs), for muon tomography. We present a detailed GEANT4 simulation of a GEM-based MT station for various scenarios of threat material detection. Cosmic ray muon tracks crossing the material are reconstructed with a point-of-closest-approach algorithm to form 3-D tomographic images of the target material. We investigate acceptance, Z-discrimination capability, effects of placement of high-Z material and shielding materials inside the cargo, and detector resolution effects for such a MT station.
Muon tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons is a promising technique for detecting and imaging heavily shielded high-Z nuclear materials such as ...enriched uranium. This technique could complement standard radiation detection portals currently deployed at international borders and ports, which are not very sensitive to heavily shielded nuclear materials. We image small targets in 3D using 2×2×2 mm 3 voxels with a minimal muon tomography station prototype that tracks muons with Gas Electron Multiplier (GEM) detectors read out in 2D with x-y microstrips of 400 μm pitch. With preliminary electronics, the GEM detectors achieve a spatial resolution of 130 μm in both dimensions. With the next GEM-based prototype station we plan to probe an active volume of ~27 liters. We present first results on reading out all 1536 microstrips of a 30×30 cm 2 GEM detector for the next muon tomography prototype with final frontend electronics and DAQ system. This constitutes the first full-size implementation of the Scalable Readout System (SRS) recently developed specifically for Micropattern Gas Detectors by the RD51 collaboration. Design of the SRS and first performance results when reading out GEM detectors are presented.
The PRad windowless gas flow target Pierce, J.; Brock, J.; Carlin, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2021, Letnik:
1003
Journal Article
Recenzirano
Odprti dostop
We report on a windowless, high-density, gas-flow target at Jefferson Lab that was used to measure rp, the root-mean-square charge radius of the proton. The target achieved its design goal of an ...areal density of 2 × 1018 atoms/cm2, with the gas uniformly distributed over the 4 cm length of the cell and less than 1% residual gas outside the cell. This design eliminated scattering from the end caps of the target cell, a problem endemic to previous measurements of the proton charge radius in electron scattering experiments, and permitted a precise, model-independent extraction of rp by reaching unprecedentedly low values of Q2, the square of the electron’s transfer of four-momentum to the proton.
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