The TOTEM modular trigger system Bagliesi, M.G.; Berretti, M.; Cecchi, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Volume:
617, Issue:
1
Journal Article
Peer reviewed
The TOTEM experiment will measure the total cross-section with the luminosity independent method and study elastic and diffractive scattering at the LHC. We are developing a modular trigger system, ...based on programmable logic, that will select meaningful events within
2.5
μ
s
. The trigger algorithm is based on a tree structure in order to obtain information compression. The trigger primitive is generated directly on the readout chip, VFAT, that has a specific fast output that gives low resolution hits information. In two of the TOTEM detectors, Roman Pots and T2, a coincidence chip will perform track recognition directly on the detector readout boards, while for T1 the hits are transferred from the VFATs to the trigger hardware. Starting from more than 2000 bits delivered by the detector electronics, we extract, in a first step, six trigger patterns of 32 LVDS signals each; we build, then, on a dedicated board, a 1-bit (L1) trigger signal for the TOTEM experiment and 16 trigger bits to the CMS experiment global trigger system for future common data taking.
We describe an analysis comparing the p¯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 √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 3.4σ 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 strong interaction scattering amplitude in pp scattering for which the significance is between 3.4σ and 4.6σ. The combined significance is larger than 5σ and is interpreted as the first observation of the exchange of a colorless, C-odd gluonic compound.
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 pseudorapidity density of charged particles dN /d is measured by the TOTEM experiment in proton-proton collisions at TeV within the range and . Data were collected in a low intensity LHC run with ...collisions occurring at a distance of 11.25 m from the nominal interaction point. The data sample is expected to include 96-97 % of the inelastic proton-proton interactions. The measurement reported here considers charged particles with MeV/c, produced in inelastic interactions with at least one charged particle in Formula omitted or . The dN /d Formula omitted has been found to decrease with , from 5.11 0.73 at to 1.81 0.56 at 6.925. Several Monte Carlo generators are compared to the data and are found to be within the systematic uncertainty of the measurement.
The first double diffractive cross-section measurement in the very forward region has been carried out by the TOTEM experiment at the LHC with a center-of-mass energy of sqrts=7 TeV. By utilizing ...the very forward TOTEM tracking detectors T1 and T2, which extend up to |η|=6.5, a clean sample of double diffractive pp events was extracted. From these events, we determined the cross section σDD=(116±25) μb for events where both diffractive systems have 4.7<|η|min<6.5.
Abstract
The proton–proton elastic differential cross section
$${\mathrm{d}}\sigma /{\mathrm{d}}t$$
d
σ
/
d
t
has been measured by the TOTEM experiment at
$$\sqrt{s}=2.76\hbox { TeV}$$
s
=
2.76
TeV
...energy with
$$\beta ^{*}=11\hbox { m}$$
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
$$0.74\hbox { GeV}^{2}$$
0.74
GeV
2
. The differential cross-section can be described with an exponential in the |
t
|-range between 0.36 and
$$0.54\hbox { GeV}^{2}$$
0.54
GeV
2
, followed by a diffractive minimum (dip) at
$$|t_{\mathrm{dip}}|=(0.61\pm 0.03)\hbox { GeV}^{2}$$
|
t
dip
|
=
(
0.61
±
0.03
)
GeV
2
and a subsequent maximum (bump). The ratio of the
$${\mathrm{d}}\sigma /{\mathrm{d}}t$$
d
σ
/
d
t
at the bump and at the dip is
$$1.7\pm 0.2$$
1.7
±
0.2
. When compared to the proton–antiproton measurement of the D0 experiment at
$$\sqrt{s} = 1.96\hbox { TeV}$$
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 proton–proton elastic differential cross section $${\mathrm{d}}\sigma /{\mathrm{d}}t$$ dσ/dt has been measured by the TOTEM experiment at $$\sqrt{s}=2.76\hbox { TeV}$$ s=2.76TeV energy ...with $$\beta ^{*}=11\hbox { m}$$ β∗=11m 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 $$0.74\hbox { GeV}^{2}$$ 0.74GeV2 . The differential cross-section can be described with an exponential in the |t|-range between 0.36 and $$0.54\hbox { GeV}^{2}$$ 0.54GeV2 , followed by a diffractive minimum (dip) at $$|t_{\mathrm{dip}}|=(0.61\pm 0.03)\hbox { GeV}^{2}$$ |tdip|=(0.61±0.03)GeV2 and a subsequent maximum (bump). The ratio of the $${\mathrm{d}}\sigma /{\mathrm{d}}t$$ dσ/dt at the bump and at the dip is $$1.7\pm 0.2$$ 1.7±0.2 . When compared to the proton–antiproton measurement of the D0 experiment at $$\sqrt{s} = 1.96\hbox { TeV}$$ s=1.96TeV , 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.
The TOTEM collaboration has measured the elastic proton-proton differential cross section Formula omitted at Formula omitted TeV LHC energy using dedicated Formula omitted m beam optics. The Roman ...Pot detectors were inserted to 10 Formula omitted distance from the LHC beam, which allowed the measurement of the range 0.04 GeV Formula omitted; 4 GeV Formula omitted Formula omitted in four-momentum transfer squared |t|. The efficient data acquisition allowed to collect about 10 Formula omitted 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 Formula omittedGeV Formula omitted in the |t|-range 0.04-0.2 GeV Formula omitted. The dip position is Formula omittedGeV Formula omitted. The differential cross section ratio at the bump vs. at the dip Formula omitted 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.
Abstract The TOTEM collaboration has measured the elastic proton-proton differential cross section $$\mathrm{d}\sigma /\mathrm{d}t$$ dσ/dt 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}})~$$ B=(20.40±0.002stat±0.01syst) GeV$$^{-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}})~$$ |tdip|=(0.47±0.004stat±0.01syst) GeV$$^{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±0.01stat 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.
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