Luminosity is a key parameter in any particle collider, and its precise determination has proven particularly challenging at hadron colliders. After introducing the concept of luminosity in its ...multiple incarnations and offering a brief survey of the pp and pp¯ colliders built to date, this article outlines the various methods that have been developed for relative-luminosity monitoring, as well as the complementary approaches considered for establishing an absolute luminosity scale. This is followed by a survey, from both a historical and a technical perspective, of luminosity determination at the ISR, the Spp̄S, the Tevatron, RHIC and the LHC. For each of these, we first delineate the interplay between the experimental context, the specificities of the accelerator, and the precision targets suggested by the physics program. We then detail how the different methods were applied to specific experimental environments and how successfully they meet the precision goals.
Gottfried sum from the ratio F2n/F2p Amaudruz, P; Arneodo, M; Arvidson, A ...
Physical review letters,
1991-May-27, Letnik:
66, Številka:
21
Journal Article
Recenzirano
Experimental results obtained at the CERN Super Proton Synchrotron on the structure-function ratio F2n/F2p in the kinematic range 0.004 < x < 0.8 and 0.4 < Q2 < 190 GeV2, together with ...the structure function F2d determined from a fit to published data, are used to derive the difference F2p(x) - F2n(x). The value of the Gottfried sum integral (F2p - F2n) dx/x = 0.240 +/- 0.016 is below the quark-parton-model expectation of 1/3.
Channeling of a 450 GeV/
c proton beam through a bent silicon crystal has found a novel application to the production of simultaneous particle beams. A pair of simultaneous, nearly-collinear beams of ...long- and short-lived neutral kaons has thereby been derived. These beams form an integral part of an experiment, NA48, at CERN, designed to measure the CP-violation parameter
ϵ′
ϵ
with high precision.
We evaluate the possible deviation (from the conventional Cahn's result) of
the phase between the one-photon-exchange and the `nuclear' high energy $pp$
scattering amplitudes in a small $t\to 0$ ...region caused by a more complicated
(not just $exp(Bt)$) behaviour of the nuclear amplitude. Furthermore we look at
the possible role of the $t$-dependence of the $\rho(t) \equiv$ Real/Imaginary
amplitude ratio. It turns out that both effects are rather small - much smaller
than to have any influence on the experimental accuracy of $\rho(t=0)$
extracted from the elastic proton-proton scattering data.
Using data taken during the year 2000 with the NA48 detector at the CERN SPS, a search for the CP violating decay K_S -> 3 pi0 has been performed. From a fit to the lifetime distribution of about 4.9 ...million reconstructed K0/K0bar -> 3 pi0 decays, the CP violating amplitude eta_000 = A(K_S -> 3 pi0)/A(K_L -> 3 pi0) has been found to be Re(eta_000) = -0.002 +- 0.011 +- 0.015 and Im(eta_000) = -0.003 +- 0.013 +- 0.017. This corresponds to an upper limit on the branching fraction of Br(K_S -> 3 pi0) < 7.4 x 10^-7 at 90% confidence level. The result is used to improve knowledge of Re(epsilon) and the CPT violating quantity Im(delta) via the Bell-Steinberger relation.
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