The performance of the NA48 detector Jeitler, M.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2002, Letnik:
478, Številka:
1
Journal Article
Recenzirano
The NA48 experiment at the SPS accelerator at CERN aims at measuring the parameter of direct CP-violation,
ε′/
ε with an accuracy of 2×10
−4. Neutral kaons are produced at two targets located at ...different distances from the detector, thus creating a “K
long” and a “K
short” beam. The experiment measures the decays of kaons from these two beams into two neutral or two charged pions.
The detection of photons from neutral-pion decay is achieved by means of a liquid-krypton calorimeter. In order to suppress the huge background from K
L
0→3π
0 decays, very good spatial, energy and time resolution are mandatory. The charged mode (K
0
L,S→π
+π
− decays) is measured with a spectrometer consisting of four drift chambers and a magnet. Decays from the two beams are distinguished by tagging the protons impinging on the second target by means of a scintillator array. Excellent time resolution and high efficiency are indispensible. Moreover, both the detector and the associated electronics operate in a high-radiation environment. This has given rise to specific problems, and the solutions adopted by NA48 are presented.
The central trigger control system of the CMS experiment at CERN Jeitler, M.; Taurok, A.; Bergauer, H. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The Level-1 (L1) Trigger of the CMS experiment uses custom-made, fast electronics, while the experiment's high-level trigger is implemented in computer farms. The Central Trigger Control System ...described in this poster receives physics triggers from the Global Trigger Logic unit, collects information from the various subdetector systems to check if they are ready to accept triggers, reduces excessive trigger rates according to preset rules and finally distributes the trigger (“Level-1 Accept”) together with timing signals to the subdetectors over the so-called “Trigger, and Timing and Control” (TTC) network of the experiment. The complete functionality of the Central Trigger Control System is implemented in one 9U-VME module and several ancillary boards for input and output functions. The system has been used successfully during CMS test runs with cosmics and beam.
The Large Hadron Collider (LHC) at CERN in Geneva, Switzerland, is the most powerful particle accelerator in the world. Its aim is to study the physics of elementary particles at the highest energies ...accessible to accelerators. It is believed that the Higgs boson (a last particle predicted by the Standard Model that is yet to be found) and the lightest particles of the Minimal Supersymmetric Model should be accessible at the LHC energies. These lectures give a short overview of the physics program and the technological challenges this collider faces.
The NA48/2 experiment at CERN collected a large sample of charged kaon decays to final states with multiple charged particles in 2003–2004. A new upper limit on the rate of the lepton number ...violating decay K±→π∓μ±μ± is reported: B(K±→π∓μ±μ±)<8.6×10−11 at 90% CL. Searches for two-body resonances X in K±→πμμ decays (such as heavy neutral leptons N4 and inflatons χ) are also presented. In the absence of signals, upper limits are set on the products of branching fractions B(K±→μ±N4)B(N4→πμ) and B(K±→π±X)B(X→μ+μ−) for ranges of assumed resonance masses and lifetimes. The limits are in the (10−11,10−9) range for resonance lifetimes below 100 ps.
We report a measurement of the direct CP violation asymmetry parameter Ag in charged kaon decays K±→π±π+π− by the NA48/2 experiment at the CERN SPS. The experiment has been designed not to be limited ...by systematics in the asymmetry measurement. Using 1.67×109 such decays collected during the 2003 run, the charge asymmetry in the Dalitz plot linear slope parameter g has been measured to be Ag=(1.7±2.9)×10−4. The precision of the result is limited by the statistics used.
We report results from the analysis of the
(
) decay by the NA48/2 collaboration at the CERN SPS, based on the total statistics of 1.13 million decays collected in 2003–2004. The hadronic form ...factors in the S- and P-wave and their variation with energy are obtained. The phase difference between the S- and P-wave states of the
ππ
system is accurately measured and allows a precise determination of
and
, the I = 0 and I = 2 S-wave
ππ
scattering lengths:
. Combination of this result with the other NA48/2 measurement obtained in the study of
decays brings an improved determination of
and the first precise experimental measurement of
, providing a stringent test of Chiral Perturbation Theory predictions and lattice QCD calculations. Using constraints based on analyticity and chiral symmetry, even more precise values are obtained:
and
.
We report on the measurement of the direct emission (DE) and interference (INT) terms of the K±→π±π0γ decay by the NA48/2 experiment at the CERN SPS. From the data collected during 2003 and 2004 ...about 600k such decay candidates have been selected. The relative amounts of DE and INT with respect to the internal bremsstrahlung (IB) contribution have been measured in the range \(0<T^{*}_{\pi }<80\) MeV: \\begin{array}{l}\mathrm{Frac_{\mathrm{DE}}}{(0<T^{*}_{\pi }<80~\mathrm{MeV})}\\3pt\quad =(3.32\pm0.15_{\mathrm{stat}}\pm 0.14_{\mathrm{sys}})\times10^{-2},\\3pt\mathrm{Frac_{\mathrm{INT}}}{(0<T^{*}_{\pi }<80~\mathrm{MeV})}\\3pt\quad =(-2.35\pm 0.35_{\mathrm{stat}}\pm0.39_{\mathrm{sys}})\times10^{-2}\end{array}\ where \(T^{*}_{\pi }\) is the kinetic energy of the charged pion in the kaon rest frame. This is the first observation of an interference term in K±→π±π0γ decays, thus allowing the normalised electric and magnetic amplitudes to be measured, giving XE=(−24±6) GeV−4, and XM=(254±9) GeV−4.In addition, a limit on the CP violating asymmetry in the K+ and K− branching ratios for this channel has been determined to be less than 1.5×10−3 at 90% confidence level.
A total of 368 415 Ξ0→Λπ0 and 31 171 Ξ0¯→Λ¯π0 were selected from data recorded in the NA48/1 experiment during 2002 data taking. From this sample, the polarization of Ξ0 and Ξ0¯ hyperons was measured ...to be PΞ0=−0.102±0.012(stat)±0.008(syst) and PΞ0¯=−0.01±0.04(stat)±0.008(syst). The dependence of PΞ0 on the Ξ0 transverse momentum with respect to the primary proton beam is also presented. With the same data sample, the ratio of Ξ0¯ and Ξ0 fluxes in proton collisions at 400 GeV/c on a beryllium target was measured.
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