The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton–proton scattering at
s
=
8
TeV
in the squared four-momentum transfer range
0.2
GeV
2
<
|
t
|
<
...1.9
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
s
=
8
TeV
yields the positions,
|
t
|
dip
=
(
0.521
±
0.007
)
GeV
2
and
|
t
|
bump
=
(
0.695
±
0.026
)
GeV
2
, as well as the cross-section values,
d
σ
/
d
t
dip
=
(
15.1
±
2.5
)
μ
b
/
GeV
2
and
d
σ
/
d
t
bump
=
(
29.7
±
1.8
)
μ
b
/
GeV
2
, for the dip and the bump, respectively.
We report on the results from the observations in the very high energy band (VHE; unk greater than or equal to 100 GeV) of the black hole X-ray binary (BHXB) Cygnus X-1. The observations were ...performed with the MAGIC telescope, for a total of 40 hr during 26 nights, spanning the period between 2006 June and November. Searches for steady Y-ray signals yielded no positive result, and upper limits to the integral flux ranging between 1% and 2% of the Crab Nebula flux, depending on the energy, have been established. We also analyzed each observation night independently, obtaining evidence of Y-ray signals at the 4.0 sigma significance level (3.2 sigma after trial correction) for 154 minutes of effective on-time (EOT) on September 24 between 20:58 and 23:41 UTC, coinciding with an X-ray flare seen by RXTE, Swift, and INTEGRAL. A search for faster-varying signals within a night resulted in an excess with a significance of 4.9 sigma (4.1 sigma after trial correction) for 79 minutes EOT between 22:17 and 23:41 UTC. The measured excess is compatible with a pointlike source at the position of Cygnus X-1 and excludes the nearby radio nebula powered by its relativistic jet. The differential energy spectrum is well fitted by an unbroken power law described as dN/(dA dt dE) = (2.3 plus or minus 0.6) x 10- super(12)(E/1TeV) super(-3.2 plus or minus 0.6). This is the first experimental evidence of VHE emission from a stellar mass black hole and therefore from a confirmed accreting X-ray binary.
Abstract
The TOTEM collaboration at the CERN LHC has measured the differential cross-section of elastic proton–proton scattering at
$$\sqrt{s} = 8\,\mathrm{TeV}$$
s
=
8
TeV
in the squared ...four-momentum transfer range
$$0.2\,\mathrm{GeV^{2}}< |t| < 1.9\,\mathrm{GeV^{2}}$$
0.2
GeV
2
<
|
t
|
<
1.9
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
$$\sqrt{s} = 8\,\mathrm{TeV}$$
s
=
8
TeV
yields the positions,
$$|t|_{\mathrm{dip}} = (0.521 \pm 0.007)\,\mathrm{GeV^2}$$
|
t
|
dip
=
(
0.521
±
0.007
)
GeV
2
and
$$|t|_{\mathrm{bump}} = (0.695 \pm 0.026)\,\mathrm{GeV^2}$$
|
t
|
bump
=
(
0.695
±
0.026
)
GeV
2
, as well as the cross-section values,
$$\left. {\mathrm{d}\sigma /\mathrm{d}t}\right| _{\mathrm{dip}} = (15.1 \pm 2.5)\,\mathrm{{\mu b/GeV^2}}$$
d
σ
/
d
t
dip
=
(
15.1
±
2.5
)
μ
b
/
GeV
2
and
$$\left. {\mathrm{d}\sigma /\mathrm{d}t}\right| _{\mathrm{bump}} = (29.7 \pm 1.8)\,\mathrm{{\mu b/GeV^2}}$$
d
σ
/
d
t
bump
=
(
29.7
±
1.8
)
μ
b
/
GeV
2
, for the dip and the bump, respectively.
The proton–proton elastic differential cross section
d
σ
/
d
t
has been measured by the TOTEM experiment at
s
=
2.76
TeV
energy with
β
∗
=
11
m
beam optics. The Roman Pots were inserted to 13 times ...the transverse beam size from the beam, which allowed to measure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer (|
t
|) from 0.36 to
0.74
GeV
2
. The differential cross-section can be described with an exponential in the |
t
|-range between 0.36 and
0.54
GeV
2
, followed by a diffractive minimum (dip) at
|
t
dip
|
=
(
0.61
±
0.03
)
GeV
2
and a subsequent maximum (bump). The ratio of the
d
σ
/
d
t
at the bump and at the dip is
1.7
±
0.2
. When compared to the proton–antiproton measurement of the D0 experiment at
s
=
1.96
TeV
, a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for the exchange of a colourless C-odd three-gluon compound state in the
t
-channel of the proton–proton and proton–antiproton elastic scattering.
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, 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.
The TOTEM T2 telescope based on triple-GEM chambers Bagliesi, M.G.; Berretti, M.; Brucken, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
The TOTEM experiment at LHC has chosen the triple Gas Electron Multiplier (GEM) technology for its T2 telescope which will provide charged track reconstruction in the pseudorapidity range
5.3
<
|
η
|
...<
6.5
and a fully inclusive trigger for inelastic events. GEMs are gas filled detectors which combine good spatial resolution with very high rate capability and a good resistance to radiation. Preliminary results of cosmic ray tests performed at CERN on final T2 modules before installation are here presented. Comparisons between real and simulated detector performance are also shown.
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