This work reports the testing of a Forward Calorimeter (FoCal) prototype based on an n-type Si pad array detector at the CERN PS accelerator. The FoCal is a proposed upgrade in the ALICE detector ...operating within the pseudorapidity range of 3.2 < \(\mathrm{\eta}\) < 5.8. It aims to measure direct photons, neutral hadrons, vector mesons, and jets for the study of gluon saturation effects in the unexplored region of low momentum fraction x (\(\mathrm{\sim10^{-5} - 10^{-6}}\)). The prototype is a \(\mathrm{8\times9}\) n-type Si pad array detector with each pad occupying one cm\(^2\) area, fabricated on a 6-in, 325~\(\mathrm{\pm 10 \thinspace \mu}\)m thick, and high-resistivity (\(\sim\)7 k\(\Omega \thinspace\) cm) Si wafer which is readout using HGCROCv2 chip. The detector is tested using pion beams of energy 10~GeV and electron beams of energy 1-5~GeV. The measurements of the Minimum Ionizing Particle (MIP) response of pions and the shower profiles of electrons are reported.
The AGILE (Advanced enerGetic Ion eLectron tElescope) project focuses on the development of a compact low-cost space-based instrument to measure the intensities of charged particles and ions in ...space. Using multiple layers of fast silicon sensors and custom front-end electronics, the instrument is designed for real-time particle identification of a large variety of elements from H to Fe and spanning energies from 1 to 100 MeV per nucleon. The robust method proposed in this work uses key defining features of electronic signals generated by charged particles (ions) traveling through silicon layers to reliably identify and characterize particles in situ. AGILE will use this real-time pulse shape discrimination technique for the first time in space based instrumentation.
We present the performance of a full-length prototype of the ALICE Forward Calorimeter (FoCal). The detector is composed of a silicon-tungsten electromagnetic sampling calorimeter with longitudinal ...and transverse segmentation (FoCal-E) of about 20\(X_0\) and a hadronic copper-scintillating-fiber calorimeter (FoCal-H) of about 5\(\lambda_{\rm int}\). The data were taken between 2021 and 2023 at the CERN PS and SPS beam lines with hadron (electron) beams up to energies of 350 (300) GeV. Regarding FoCal-E, we report a comprehensive analysis of its response to minimum ionizing particles across all pad layers. The longitudinal shower profile of electromagnetic showers is measured with a layer-wise segmentation of 1\(X_0\). As a projection to the performance of the final detector in electromagnetic showers, we demonstrate linearity in the full energy range, and show that the energy resolution fulfills the requirements for the physics needs. Additionally, the performance to separate two-showers events was studied by quantifying the transverse shower width. Regarding FoCal-H, we report a detailed analysis of the response to hadron beams between 60 and 350 GeV. The results are compared to simulations obtained with a Geant4 model of the test beam setup, which in particular for FoCal-E are in good agreement with the data. The energy resolution of FoCal-E was found to be lower than 3% at energies larger than 100 GeV. The response of FoCal-H to hadron beams was found to be linear, albeit with a significant intercept that is about factor 2 larger than in simulations. Its resolution, which is non-Gaussian and generally larger than in simulations, was quantified using the FWHM, and decreases from about 16% at 100 GeV to about 11% at 350 GeV. The discrepancy to simulations, which is particularly evident at low hadron energies, needs to be further investigated.
In order to improve the time precision of detectors based on diamonds sensors we have built a detector with two scCVD layers connected in parallel to the same amplifier. This note describes the ...design and the first measurements of such a prototype performed on a particle beam at CERN. With this different configuration we have obtained an improvement on the timing precision of a factor of 1.6-1.7 with respect to a single layer scCVD diamond detector.
The TOTEM collaboration at the CERN LHC has measured the differential
cross-section of elastic proton-proton scattering at $\sqrt{s} = 8\ {\rm TeV}$
in the squared four-momentum transfer range $0.2\ ...{\rm GeV^{2}} < |t| < 1.9\
{\rm GeV^{2}}$. This interval includes the structure with a diffractive minimum
("dip") and a secondary maximum ("bump") that has also been observed at all
other LHC energies, where measurements were made. A detailed characterisation
of this structure for $\sqrt{s} = 8\ {\rm TeV}$ yields the positions, $|t|_{\rm
dip} = (0.521 \pm 0.007)\ {\rm GeV^2}$ and $|t|_{\rm bump} = (0.695 \pm 0.026)\
{\rm GeV^2}$, as well as the cross-section values, ${{\rm d}\sigma/{\rm d}
t}_{\rm dip} = (15.1 \pm 2.5)\ {\rm{\mu b/GeV^2}}$ and ${{\rm d}\sigma/{\rm d}
t}_{\rm bump} = (29.7 \pm 1.8)\ {\rm{\mu b/GeV^2}}$, for the dip and the bump,
respectively.
The MIP Timing Detector will provide additional timing capabilities for detection of minimum ionizing particles (MIPs) at CMS during the High Luminosity LHC era, improving event reconstruction and ...pileup rejection. The central portion of the detector, the Barrel Timing Layer (BTL), will be instrumented with LYSO:Ce crystals and Silicon Photomultipliers (SiPMs) providing a time resolution of about 30 ps at the beginning of operation, and degrading to 50-60 ps at the end of the detector lifetime as a result of radiation damage. In this work, we present the results obtained using a 120 GeV proton beam at the Fermilab Test Beam Facility to measure the time resolution of unirradiated sensors. A proof-of-concept of the sensor layout proposed for the barrel region of the MTD, consisting of elongated crystal bars with dimensions of about 3 x 3 x 57 mm\(^3\) and with double-ended SiPM readout, is demonstrated. This design provides a robust time measurement independent of the impact point of the MIP along the crystal bar. We tested LYSO:Ce bars of different thickness (2, 3, 4 mm) with a geometry close to the reference design and coupled to SiPMs manufactured by Hamamatsu and Fondazione Bruno Kessler. The various aspects influencing the timing performance such as the crystal thickness, properties of the SiPMs (e.g. photon detection efficiency), and impact angle of the MIP are studied. A time resolution of about 28 ps is measured for MIPs crossing a 3 mm thick crystal bar, corresponding to an MPV energy deposition of 2.6 MeV, and of 22 ps for the 4.2 MeV MPV energy deposition expected in the BTL, matching the detector performance target for unirradiated devices.
Phys. Rev. Lett. 127, 062003 (2021) We describe an analysis comparing the $p\bar{p}$ elastic cross section as
measured by the D0 Collaboration at a center-of-mass energy of 1.96 TeV to that
in $pp$ ...collisions as measured by the TOTEM Collaboration at 2.76, 7, 8, and 13
TeV using a model-independent approach. The TOTEM cross sections extrapolated
to a center-of-mass energy of $\sqrt{s} =$ 1.96 TeV are compared with the D0
measurement in the region of the diffractive minimum and the second maximum of
the $pp$ cross section. The two data sets disagree at the 3.4$\sigma$ level and
thus provide evidence for the $t$-channel exchange of a colorless, $C$-odd
gluonic compound, also known as the odderon. We combine these results with a
TOTEM analysis of the same $C$-odd exchange based on the total cross section
and the ratio of the real to imaginary parts of the forward elastic scattering
amplitude in $pp$ scattering. The combined significance of these results is
larger than 5$\sigma$ and is interpreted as the first observation of the
exchange of a colorless, $C$-odd gluonic compound.
