Abstract The TOTEM collaboration has measured the elastic proton-proton differential cross section $$\mathrm{d}\sigma /\mathrm{d}t$$ d σ / d t at $$\sqrt{s}=13$$ s = 13 TeV LHC energy using ...dedicated $$\beta ^{*}=90$$ β ∗ = 90 m beam optics. The Roman Pot detectors were inserted to 10 $$\sigma $$ σ distance from the LHC beam, which allowed the measurement of the range 0.04 GeV $$^{2}$$ 2 ; 4 GeV $$^{2}$$ 2 $$$$ in four-momentum transfer squared | t |. The efficient data acquisition allowed to collect about 10 $$^{9}$$ 9 elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-| t | tail. The average nuclear slope has been found to be $$B=(20.40 \pm 0.002^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$ B = ( 20.40 ± 0 . 002 stat ± 0 . 01 syst ) GeV $$^{-2}$$ - 2 in the | t |-range 0.04–0.2 GeV $$^{2}$$ 2 . The dip position is $$|t_{\mathrm{dip}}|=(0.47 \pm 0.004^{\mathrm{stat}} \pm 0.01^{\mathrm{syst}})~$$ | t dip | = ( 0.47 ± 0 . 004 stat ± 0 . 01 syst ) GeV $$^{2}$$ 2 . The differential cross section ratio at the bump vs. at the dip $$R=1.77\pm 0.01^{\mathrm{stat}}$$ R = 1.77 ± 0 . 01 stat has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.
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, Volume:
718
Journal Article
Peer reviewed
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.
The TOTEM experiment has made a precise measurement of the elastic proton–proton differential cross-section at the centre-of-mass energy s=8 TeV based on a high-statistics data sample obtained with ...the β⁎=90 m optics. Both the statistical and systematic uncertainties remain below 1%, except for the t-independent contribution from the overall normalisation. This unprecedented precision allows to exclude a purely exponential differential cross-section in the range of four-momentum transfer squared 0.027<|t|<0.2 GeV2 with a significance greater than 7 σ. Two extended parametrisations, with quadratic and cubic polynomials in the exponent, are shown to be well compatible with the data. Using them for the differential cross-section extrapolation to t=0, and further applying the optical theorem, yields total cross-section estimates of (101.5±2.1) mb and (101.9±2.1) mb, respectively, in agreement with previous TOTEM measurements.
An analog front-end in 130 (nm) CMOS technology was developed for the readout of triple-GEM detectors in the CMS experiment at CERN. The front-end has programmable peaking time - 15, 25, 35 and 45 ...(ns) - and gain - 48, 16.4 and 8.6 (mV/fC) - and is able to support a detector capacitance ranging from 0 to 120 (pF). In the design, many optimization techniques have been used to minimize the power consumption for given noise and timing requirements. Consequently, a single front-end channel consumes 790 (μA), and achieves an equivalent noise chargeof 620 (e-) at 0 (pF) detector capacitance with a noise slope of 33 (e-/pF). In order to simplify the peaking time programmability, an OTA-C based shaperwas used in the analog chain. The entire design hasbeen made radiation hard against TID. A chip comprising 129 front-end channels was fabricated and tested.
VFAT3 is a front-end ASIC designed for the readout of GEM detectors in the CMS Muon system. The strategy for the chip design was to design the full chip at once but provide extensive test and debug ...facilities for individual characterization of each internal chip module. The verification platform consists of three parts; namely the software (running on a PC), the firmware (designed for a Kintex-7 FPGA development board) and a selection of VFAT3 dedicated hardware boards for the different stages of verification. The system was designed to accommodate all of the steps needed to fully test the chip. The first step is the functional testing for which only rather simple functions are needed. For the functional testing. the software has an interactive interface to communicate with the chip through the FPGA. The requirements for the hardware are mostly the possibility for the use of the main communication channels. For the characterization of the chip, the software offers a possibility to easily generate lists of routine instructions that can be uploaded to the FPGA and run as synchronous commands. This allows for example the scanning of the chip's internal calibration DACs and creation of S-curves for all of the front-end channels. The hardware boards of the system allows access to the vast amount of test pads needed for the characterization and debug of the chip. The production tests require concatenated test routines where speed and execution efficiency are crucial. The software and the firmware of the system were designed to allow flexible evolution to increase the efficiency of complicated test routines.
The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton-proton scattering at Formula omitted in the squared four-momentum transfer range Formula omitted. ...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 Formula omitted yields the positions, Formula omitted and Formula omitted, as well as the cross-section values, Formula omitted and Formula omitted, for the dip and the bump, respectively.
The TOTEM collaboration has measured the proton–proton total cross section at
s
=
13
TeV
with a luminosity-independent method. Using dedicated
β
∗
=
90
m
beam optics, the Roman Pots were inserted ...very close to the beam. The inelastic scattering rate has been measured by the T1 and T2 telescopes during the same LHC fill. After applying the optical theorem the total proton–proton cross section is
σ
tot
=
(
110.6
±
3.4
) mb, well in agreement with the extrapolation from lower energies. This method also allows one to derive the luminosity-independent elastic and inelastic cross sections:
σ
el
=
(
31.0
±
1.7
)
mb
and
σ
inel
=
(
79.5
±
1.8
)
mb
.
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