The Gigatracker, the silicon beam tracker for the NA62 experiment at CERN Federici, L.; Aglieri Rinella, G.; Alvarez Feito, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Volume:
958
Journal Article
Peer reviewed
Open access
The Gigatracker is the NA62 beam tracker. It is made of three 63.1mm×29.3mm stations of 300μm×300μm hybrid silicon pixel detectors installed in vacuum (∼10−6mbar). The beam particles, flowing at ...750MHz, are traced in 4-dimensions by mean of time-stamping pixels with a design resolution of 200ps. This performance has to be maintained despite the beam irradiation amounting to a yearly fluence of 2×10141MeVneq∕cm2. The detector material minimization is paramount, as the detector faces the full beam. The station material budget is reduced to 0.5%X0 by using (HEP world first) micro-channels cooling. We will describe the detector design and performances during the NA62 runs.
The NA62 GigaTracker Aglieri Rinella, G.; Feito, D. Alvarez; Arcidiacono, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2017, Volume:
845
Journal Article
Peer reviewed
Open access
The GigaTracker is a hybrid silicon pixel detector built for the NA62 experiment aiming at measuring the branching fraction of the ultra-rare kaon decay K+→π+νν¯ at the CERN SPS. The detector has to ...track particles in a beam with a flux reaching 1.3MHz/mm2 and provide single-hit timing with 200ps RMS resolution for a total material budget of less than 0.5% X0 per station. The tracker comprises three 60.8mm×27mm stations installed in vacuum (∼10−6mbar) and cooled with liquid C6F14 circulating through micro-channels etched inside a few hundred micron thick silicon plates. Each station is composed of a 200μm thick silicon sensor read out by 2×5 custom 100μm thick ASICs, called TDCPix. Each chip contains 40×45 asynchronous pixels, 300μm×300μm each and is instrumented with 100ps bin time-to-digital converters. In order to cope with the high rate, the TDCPix is equipped with four 3.2Gb/s serialisers sending out the data. We will describe the detector and the results from the 2014 and 2015 NA62 runs.
Pion–Muon separation with a RICH prototype for the NA62 experiment Angelucci, B.; Anzivino, G.; Avanzini, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2010, Volume:
621, Issue:
1
Journal Article
Peer reviewed
The NA62 experiment at CERN, aimed to measure
K
+
→
π
+
ν
ν
¯
branching fraction (O(10
−10)), relies on a Neon based RICH detector for
π
/
μ
separation, time measurement and level 0 trigger. The ...experimental requirements for this detector are: a muon contamination in pion samples lower than 5×10
−3 in the momentum range 15–35
GeV/
c and a time resolution on the charged track better than 100
ps. A prototype of such a detector was built and tested in 2009; it consists of a full length (
≈
18
m
) Ne filled vessel equipped with a spherical mirror and 414 PMs on its focal plane, located about 17
m upstream of the mirror. This prototype was tested at CERN SPS on a positive hadron beam, in the required momentum range, to measure the
π
/
μ
separation and to confirm the time resolution obtained with a previous prototype; the
μ
misidentification probability is about 0.7% and the time resolution is better than 100
ps in the whole momentum range.
Construction and test of a RICH prototype for the NA62 experiment Anzivino, G.; Biino, C.; Bizzeti, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2008, Volume:
593, Issue:
3
Journal Article
Peer reviewed
A RICH prototype has been constructed and tested. The detector was cylindrical, 17
m long and 60
cm diameter, filled with neon gas at atmospheric pressure. A spherical mirror with 17
m focal length ...was used and 96 photomultipliers were placed in the mirror focal plane. The prototype was exposed to a
200
GeV
/
c
momentum negative beam derived from the CERN SPS in the 2007 fall. The performances of the detector in terms of Cherenkov angle resolution, number of photoelectrons and time resolution are presented.
Combined measurements of the production and decay rates of the Higgs boson, as well as its couplings to vector bosons and fermions, are presented. The analysis uses the LHC proton–proton collision ...data set recorded with the CMS detector in 2016 at
s
=
13
Te
, corresponding to an integrated luminosity of 35.9
fb
-
1
. The combination is based on analyses targeting the five main Higgs boson production mechanisms (gluon fusion, vector boson fusion, and associated production with a
W
or
Z
boson, or a top quark-antiquark pair) and the following decay modes:
H
→
γ
γ
,
Z
Z
,
W
W
,
τ
τ
,
b
b
, and
μ
μ
. Searches for invisible Higgs boson decays are also considered. The best-fit ratio of the signal yield to the standard model expectation is measured to be
μ
=
1.17
±
0.10
, assuming a Higgs boson mass of
125.09
Ge
. Additional results are given for various assumptions on the scaling behavior of the production and decay modes, including generic parametrizations based on ratios of cross sections and branching fractions or couplings. The results are compatible with the standard model predictions in all parametrizations considered. In addition, constraints are placed on various two Higgs doublet models.
A search for invisible decays of a Higgs boson is performed using proton-proton collision data collected with the CMS detector at the LHC in 2016 at a center-of-mass energy s=13TeV, corresponding to ...an integrated luminosity of 35.9fb−1. The search targets the production of a Higgs boson via vector boson fusion. The data are found to be in agreement with the background contributions from standard model processes. An observed (expected) upper limit of 0.33(0.25), at 95% confidence level, is placed on the branching fraction of the Higgs boson decay to invisible particles, assuming standard model production rates and a Higgs boson mass of 125.09 GeV. Results from a combination of this analysis and other direct searches for invisible decays of the Higgs boson, performed using data collected at s=7, 8, and 13 TeV, are presented. An observed (expected) upper limit of 0.19(0.15), at 95% confidence level, is set on the branching fraction of invisible decays of the Higgs boson. The combined limit represents the most stringent bound on the invisible branching fraction of the Higgs boson reported to date. This result is also interpreted in the context of Higgs-portal dark matter models, in which upper bounds are placed on the spin-independent dark-matter-nucleon scattering cross section.
Observation of t t ¯ H Production Erö, J.; Flechl, M.; Schieck, J. ...
Physical review letters,
06/2018, Volume:
120, Issue:
23
Journal Article
Peer reviewed
Open access
Here, the observation of Higgs boson production in association with a top quark-antiquark pair is reported, based on a combined analysis of proton-proton collision data at center-of-mass energies of ...√s=7, 8, and 13 TeV, corresponding to integrated luminosities of up to 5.1, 19.7, and 35.9 fb-1, respectively. The data were collected with the CMS detector at the CERN LHC. The results of statistically independent searches for Higgs bosons produced in conjunction with a top quark-antiquark pair and decaying to pairs of W bosons, Z bosons, photons, τ leptons, or bottom quark jets are combined to maximize sensitivity. An excess of events is observed, with a significance of 5.2 standard deviations, over the expectation from the background-only hypothesis. The corresponding expected significance from the standard model for a Higgs boson mass of 125.09 GeV is 4.2 standard deviations. The combined best fit signal strength normalized to the standard model prediction is1.26+0.31–0.26.
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