501 research outputs found
Nucleon Structure Functions from ν_µ-Fe Interactions and a Study of the Valence Quark Distribution
No full textData were taken in 1979-80 by the CCFRR high energy neutrino experiment at Fermilab. A total of 150,000 neutrino and 23,000 antineutrino charged current events in the approximate energy range 25 < Ev < 250 GeV are measured and analyzed. The structure functions F2 and xF3 are extracted for three assumptions about σL/σT: R = 0., R = 0.1 and R = a QCD based expression. Systematic errors are estimated and their significance is discussed. Comparisons or the X and Q2 behaviour or the structure functions with results from other experiments are made.
We find that statistical errors currently dominate our knowledge of the valence quark distribution, which is studied in this thesis. xF3 from different experiments has, within errors and apart from level differences, the same dependence on x and Q2, except for the HPWF results. The CDHS F2 shows a clear fall-off at low-x from the CCFRR and EMC results, again apart from level differences which are calculable from cross-sections.
The result for the the GLS rule is found to be 2.83 ± .15 ± .09 ± .10 where the first error is statistical, the second is an overall level error and the third covers the rest of the systematic errors. QCD studies of xF3 to leading and second order have been done. The QCD evolution of xF3, which is independent of R and the strange sea, does not depend on the gluon distribution and fits yield
ʌLO = 88+163-78 +113-70MeV
The systematic errors are smaller than the statistical errors. Second order fits give somewhat different values of ʌ, although αs (at Q20 = 12.6 GeV2) is not so different.
A fit using the better determined F2 in place of xF3 for x > 0.4 i.e., q = 0 in that region, gives
ʌLO = 266+114-104 +85-79MeV
Again, the statistical errors are larger than the systematic errors. An attempt to measure R was made and the measurements are described. Utilizing the inequality q(x) ≥ 0 we find that in the region x > .4 R is less than 0.55 at the 90% confidence level.</p
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Fermilab Steering Group Report
No full textThe Fermilab Steering Group has developed a plan to keep U.S. accelerator-based particle physics on the pathway to discovery, both at the Terascale with the LHC and the ILC and in the domain of neutrinos and precision physics with a high-intensity accelerator. The plan puts discovering Terascale physics with the LHC and the ILC as Fermilab's highest priority. While supporting ILC development, the plan creates opportunities for exciting science at the intensity frontier. If the ILC remains near the Global Design Effort's technically driven timeline, Fermilab would continue neutrino science with the NOVA experiment, using the NuMI (Neutrinos at the Main Injector) proton plan, scheduled to begin operating in 2011. If ILC construction must wait somewhat longer, Fermilab's plan proposes SNuMI, an upgrade of NuMI to create a more powerful neutrino beam. If the ILC start is postponed significantly, a central feature of the proposed Fermilab plan calls for building an intense proton facility, Project X, consisting of a linear accelerator with the currently planned characteristics of the ILC combined with Fermilab's existing Recycler Ring and the Main Injector accelerator. The major component of Project X is the linac. Cryomodules, radio-frequency distribution, cryogenics and instrumentation for the linac are the same as or similar to those used in the ILC at a scale of about one percent of a full ILC linac. Project X's intense proton beams would open a path to discovery in neutrino science and in precision physics with charged leptons and quarks. World-leading experiments would allow physicists to address key questions of the Quantum Universe: How did the universe come to be? Are there undiscovered principles of nature: new symmetries, new physical laws? Do all the particles and forces become one? What happened to the antimatter? Building Project X's ILC-like linac would offer substantial support for ILC development by accelerating the industrialization of ILC components in the U.S. and creating an engineering opportunity for ILC cost reductions. It offers an early and tangible application for ILC R&D in superconducting technology, attracting participation from accelerator scientists worldwide and driving forward the technology for still higher-energy accelerators of the future, such as a muon collider. To prepare for a future decision, the Fermilab Steering Group recommends that the laboratory seek R&D support for Project X, in order to produce an overall design of Project X and to spur the R&D and industrialization of ILC linac components needed for Project X. Advice from the High Energy Physics Advisory Panel will guide any future decision to upgrade the Fermilab accelerator complex, taking into account developments affecting the ILC schedule and the continuing evaluation of scientific priorities for U.S. particle physics. Fermilab should also work toward increased resources for longer-term future accelerators such as a muon collider, aiming at higher energies than the ILC would provide
Hydrostatic Level System For Slow Ground Motion Studies At Fermilab And Slac
No full textA series of new ground motion studies using an upgraded hydrostatic level system are planned at Fermilab and SLAC in collaboration with BINP. To better characterize both the spatial and temporal characteristics of slow ground motion, these studies will use large number of probes and will also be performed in several geologically different locations. The hydrostatic level system used in ongoing measurements near Fermilab suffers from uncertainty of temperature fluctuation effects. This paper presents improvements to be incorporated into the upgraded hydrostatic level system, present status, and the plan for experimental studies
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Computing and data handling recent experiences at Fermilab and SLAC
No full textComputing has become evermore central to the doing of high energy physics. There are now major second and third generation experiments for which the largest single cost is computing. At the same time the availability of cheap'' computing has made possible experiments which were previously considered infeasible. The result of this trend has been an explosion of computing and computing needs. I will review here the magnitude of the problem, as seen at Fermilab and SLAC, and the present methods for dealing with it. I will then undertake the dangerous assignment of projecting the needs and solutions forthcoming in the next few years at both laboratories. I will concentrate on the offline'' problem; the process of turning terabytes of data tapes into pages of physics journals. 5 refs., 4 figs., 4 tabs
Fermilab Contributions to the FFTB
No full textThe Final Focus Test Beam (FFTB) project at SLAC is a demonstration of the feasibility of making the extremely small spot sizes needed for future e + e - linear colliders. Fermilab joined the FFTB collaboration in late 1993. This paper describes the Fermilab contributions to FFTB, emphasizing the work on lattice diagnostics. I. Introduction There has been an ongoing involvement by Fermilab in work on high energy e + e - linear colliders [1]. In 1993 Fermilab joined the Final Focus Test Beam Collaboration. The FFTB [2] is an experiment to demonstrate the feasibility of making the small beam spot sizes that are required for the success any future linear collider project. The experiment has already yielded impressive results [3] and has shown that the demagnifications needed for the NLC design are feasible. Fermilab joined the collaboration after almost all of the hardware was already installed. However an earlier engineering run indicated the need for an additional x - y halo collima..
Exclusive [Rho] 0 and [Phi] muoproduction at large Q 2
No full textArneodo M, Arvidson A, Badelek B, et al. Exclusive [Rho] 0 and [Phi] muoproduction at large Q 2. Nucl.Phys. B. 1994;429(3):503-529
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A 4 to 0.1 nm FEL Based on the SLAC Linac
No full textThe author show that using existing electron gun technology and a high energy linac like the one at SLAC, it is possible to build a Free Electron Laser operating around the 4 nm water window. A modest improvement in the gun performance would further allow to extend the FEL to the 0.1 nm region. Such a system would produce radiation with a brightness many order of magnitude above that of any synchrotron radiation source, existing or under construction, with laser power in the multigawatt region and subpicosecond pulse length
Theory-Ladenness of Observation in the Experimental Context
No full textFocusing on the discovery of weak currents, the current debate on the theory-ladenness of observation in modern physics might be too narrow, as it concerns only the last stage of a complex experimental process and statistical methods required to analyze data. The scope of the debate should be extended to include broader experimental conditions that concern the design of the apparatus and different levels of the detection process. These neglected conditions often decisively delimit experiments long before the last stage has been reached, thus predetermining the extent of the dependence of data production on the theory. I explain the nature of these conditions and the theory-ladenness tendencies they produce, noting how they affect the last stage of the data analysis and providing some relevant examples
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Fermilab research Program 1976
No full textThis collection of one-page summaries of Fermilab proposals is intended to serve as a way station between the experiment number with its short title and the full proposal. It is not intended to be a review of the Fermilab experimental program. Just as an abstract of a journal article embodies the main points of the article, so these one-page summaries are intended to convey the major points of a proposal. These should include its physics justification, a brief description of the apparatus and the demands that the experiment will make on the Laboratory. Of course these summaries are not intended to take the place of the proposal itself which is the primary document available in the Fermilab library and at SLAC, BNL and CERN. Individual copies should be obtained from the spokesman of the experiment whose name is underlined in these summaries. Summaries for all experiments and pending proposals are included. These comprise approved, unconsidered and deferred proposals. Rejected, withdrawn and inactive proposals are not included. It is the experimenters themselves who are best able to write the summary and in most cases that is what was done. For the early proposals and those cases where repeated cajoling could not produce one from the experimenters, the summary was prepared by a Fermilab staff member and then sent to the spokesman for comment. All proposals submitted before the May 7, 1976 deadline for consideration at the extended summer meeting of our Program Advisory Committee are included. It is not intended that this volume be updated annually but perhaps only reissued when the previous ones becomes hopelessly obsolete
Testing the standard model at future high energy colliders
No full textThroughout this thesis we test some aspects of the Standard Model (SM) at future high energy colliders. We start by examining the SU(2)x U(l) non-abelian nature of the SM. We consider the effect of anomalous couplings on the reaction e(^+)e(^-) → W(^+)W-γ, at s = 200 GeV, where the photon is soft. We show that the dependence on the anomalous couplings is of the same order as, but different from, the dependence of the leading order e(^+)e(^-) → W(^+)W(^-) cross section. We therefore argue that the two processes are complementary in providing precision tests of the Standard Model electroweak vertices. We also study the same process, e(^+)e(^-) → W(^+)W(^-)γ, at high-energy e(^+)e(^-) colliders to investigate the effect of genuine quartic W(^+)W(^-)γγ and W(^+)W(^-)Zγ anomalous couplings on the cross section. Deviations from the Standard Model predictions are quantified. We show how bounds on the anomalous couplings can be improved by choosing specific initial state helicity combinations. The dependence of the anomalous contributions on the collider energy is studied. We then proceed to present a detailed analysis of soft photon radiation in e(^+)e(^-) → tt → bW(^+)bW(^-). The radiation pattern is shown to depend sensitively on the top mass, width and energy, as well as the relative orientation of the initial and final state particles. Optimum conditions in which initial state radiation is minimised and the radiation pattern has the richest structure are discussed. Finally, the Higgs sector of the SM is visited, where the production of the SM Higgs ø with intermediate mass at the proposed CERN LEPOLHC ep collider in γq(q) → W(^±)øq’(q), γq(q) → Zºøq(q) and gγ → qqø events is studied. This is done for all possible (massive) flavours of the quarks q(q') and using photons generated via Compton back-scattering of laser light. We study signatures in which the Higgs decays to bb-pairs and the electroweak vector bosons W(^±) and Zº decay either hadronically or leptonically. All possible backgrounds to these signals are also computed
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