33357835
Comparison of PMTs from three different manufacturers for the CMS-HF forward calorimeter
The builders of the CMS forward hadron calorimeter established a set of specifications for readout PMTs that reflected the physics goals and mechanical needs of the CMS experiment. Three manufacturers, Hamamatsu, Photonis (Philips), and Electron Tubes (EMI), provided candidate PMTs based on these initial requirements. Timing, gain, dark current properties, and single photoelectron spectra of these candidate PMTs were measured. Results show that Hamamatsu PMTs (R7525HA) conform best to the specifications of the Hadron-Forward (HF) Calorimeter.
124078930
Muon Capture in Hydrogen
Abstract : An experiment to measure the muon capture rate in liquid hydrogen was carried out using scintillation counter techniques. The experiment tests muon-electron universality in interaction with a proton at a momentum transfer of 100 MeV/c. The use of ultra-pure liquid hydrogen, a purified muon beam, neutron-gamma ray discriminating detectors and oscilloscope photography made possible the detection of the 5.2 MeV neutron from the relatively improbable capture reaction (mu + p yields n + nu). The muon molecular formation rate was measured in an independent experiment, but the present result is relatively insensitive to it. The stability of the muon molecular ortho state against transitions to the para ground state for times comparable to the free muon life-time is confirmed. The experimental result of the capture rate measurement, 464 + or - 42 per second is compared with 562 + or - 60 per second, the rate expected on the basis of the conserved vector current theory, muon-electron universality and the accepted value of the "induced pseudo scalar" coupling constant.
139640917
Effects of Channel Failure Rates on the Jet Reconstruction Efficiencies an Resolutions in an Fe HF Calorimeter
121981552
Observation and study of centrally produced pion clusters in 28. 5-GeV/c p-p interactions
A double-arm spectrometer is used to identify a pion cluster produced in central p-p collisions at 28.5 GeV/c. Cluster properties studied are angular momentum, quantum statistics, multiplicity, and effective mass. There is some speculation on the production mechanism. (AIP)
121141376
Charged Multiplicity Associated with Transverse Momentum of a Leading Proton in pp at 28.5 GEV/C
We have measured the mean charged multiplicity nCH as a function of transverse momentum p⊥ of the forward proton in the reaction p + p ⇒ p + MM for five intervals of missing mass MM using our Multiparticle Argo Spectrometer System. We observe an increase of nCH for p⊥ > 1 GeV/c.
125174279
Design and performance of the multiparticle argo spectrometer system
Abstract The Multiparticle Argo Spectrometer System, MASS, consists of a magnetic vertex spectrometer, two external trigger spectrometers, an on-line monitoring system and an off-line data analysis chain. The performance of MASS has been evaluated from physics data taken in a study of 28.5 GeV/ c pp collisions covering a large range of transverse momentum.
118451469
Relational Quadrilateralland. Analogues of Isospin and Hypercharge
I consider the momenta and conserved quantities for CP^2 interpreted as the space of quadrilaterals. This builds on seminar I and II's kinematics via making use of MacFarlane's work considering the SU(3)-like (and thus particle physics-like) conserved quantities that occur for CP^2. I perform the additional step of further interpreting that as the configuration space of all relational quadrilaterals and thus an interesting toy model for whole-universe, relational and geometrodynamical-analogue physics. I also provide the Kuchar observables for the quadrilateral, which is a particular resolution of the Problem of Observables. I study HO-like and highly symmetric potentials. I also provide some exact solutions and qualitative behaviours for dynamics on CP^2. In each case, I reinterpret the results in terms of quadrilaterals. This paves the way for the quantum mechanical study of the relational quadrilateral and for investigations of a number of Problem of Time strategies and of a number of other foundational and qualitative investigations of Quantum Cosmology.
18007446
Foundations of relational particle dynamics
Relational particle dynamics include the dynamics of pure shape and cases in which absolute scale or absolute rotation are additionally meaningful. These are interesting as regards the absolute versus relative motion debate as well as the discussion of conceptual issues connected with the problem of time in quantum gravity. In spatial dimensions 1 and 2, the relative configuration spaces of shapes are n-spheres and complex projective spaces, from which knowledge I construct natural mechanics on these spaces. I also show that these coincide with Barbour's indirectly constructed relational dynamics by performing a full reduction on the latter. Then the identification of the configuration spaces as n-spheres and complex projective spaces, for which spaces much mathematics is available, significantly advances the understanding of Barbour's relational theory in spatial dimensions 1 and 2. I also provide the parallel study of a new theory for which the position and scale are purely relative but the orientation is absolute. The configuration space for this is an n-sphere regardless of the spatial dimension, which renders this theory a more tractable arena for investigation of implications of scale invariance than Barbour's theory itself.
117105066
PDE system approach to large extra dimensions
We explore some foundational issues regarding the splitting of D-dimensional Einstein Field Equations (EFE’s) with respect to timelike and spacelike (D - 1)-dimensional hypersurfaces, first without and then with thin matter sheets such as branes. We begin to implement methodology, that is well-established for the GR Cauchy and initial value problems (CP and IVP), in the new field of GR-based braneworlds, identifying and comparing many different choices of procedure. We abridge fragmentary parts of the literature of embeddings, putting the Campbell–Magaard theorem into context. We recollect and refine arguments why York and not elimination methods are used for the GR IVP. We compile a list of numerous mathematical and physical impasses to using timelike splits, whereas spacelike splits are known to be well-behaved. We however pursue both options to make contact with the current braneworld literature which is almost entirely based on timelike splits. In our study of timelike splits, we look at the Shiromizu–Maeda–Sasaki braneworld by means of reformulations which emphasize different aspects from the original formulation. We show that what remains of the York method in the timelike case generalizes heuristic bulk construction schemes. We formulate timelike (brane) versions of the thin sandwich conjecture. We discuss whether it is plausible to remove singularities by timelike embeddings. We point out how the braneworld geodesic postulates lead to futher difficulties with the notion of singularities than in GR where these postulates are simpler. Having argued for the use of the spacelike split, we study how to progress to the construction of more general data sets for spaces partially bounded by branes. Boundary conditions are found and algorithms provided. Working with (finitely) thick branes would appear to facilitate such a study.
14761899
Leibniz--Mach foundations for GR and fundamental physics
Consider the configuration space Q for some physical system, and a continuous group of transformations G whose action on the configurations is declared to be physically irrelevant. Implement G indirectly by adjoining 1 auxiliary g per independent generator of G to Q, by writing the system's action in an arbitrary G-frame (G-AF), and then passing to the quotient Q/G thanks to the constraints encoded by g-variation. I show that this G-AF principle supercedes (and indeed leads to a derivation of) the Barbour--Bertotti (BB) best matching principle. My other consideration is that absolute external time is meaningless for the universe as a whole. For various choices of Q and G, these lead to BB's proposed absolute structure free replacement of Newtoninan mechanics, to Gauge Theory and to the 3-space approach (TSA) formulation of GR. For the latter with matter fields, I discuss the SR postulates, Principle of Equivalence (POE) and simplicity postulates. I explain how a full enough set of fundamental matter fields to describe nature can be accommodated in the TSA, and compare the TSA with the `split spacetime formulation' of Kuchar. I explain the emergence of broken and unbroken Gauge Theories as a consequence of the POE. I also consider as further examples of the G-AF principle the further quotienting out of conformal transformations (CT) or volume preserving CT. Depending on which choices are made, this leads to York's initial value formulation (IVF) of GR, new alternative foundations for it, or alternative theories of gravity built out of similar conformal mathematics which nevertheless admit no GR-like spacetime interpretation.
18688326
Reformulation and interpretation of the SMS braneworld
We reformulate the Shiromizu, Maeda and Sasaki (SMS) braneworlds within the framework of the five-dimensional Einstein equations. In many applications of the braneworld Einstein field equations, the Weyl term is attributed to the bulk, thus splitting the non-Einsteinian terms into 'bulk' and 'brane' terms. Here by employing standard geometrical identities, we show that such a split is non-unique, since they get mixed up in different formulations. An important consequence of this non-uniqueness is that even though the full brane-bulk systems in all such formulations are completely equivalent, important differences can arise were one to truncate different formulations by throwing away the associated 'bulk' terms. This is particularly likely to be the case in more general anisotropic/inhomogeneous settings with non-AdS bulks, in which the common truncation of the SMS (which throws away the Weyl term) would not coincide with the full system. We emphasize that rather than providing support for any particular truncation, these differences show clearly the dangers of using any truncated equations and provide a strong argument in favour of studying the full brane–bulk system. The different formulations we provide also permit different ways of approaching the full brane–bulk system which may greatly facilitate its study. An example of this is the second-order nature of the formulations given here as opposed to SMS's formulation which is third order.