Recursos de colección

Caltech Authors (163.728 recursos)

Repository of works by Caltech published authors.

Status = Unpublished

Mostrando recursos 1 - 20 de 1.812

  1. Pion Photoproduction Data Below 1.5 GeV

    Beale, J. T.; Ecklund, S. D.; Walker, R. L.

  2. Selective Detectors for High Energy Photons and Electrons

    Heusch, Clemens A.; Prescott, Charles Y.
    For fast identification of high-energy electrons and photons in heavy backgrounds, a counter was developed consisting of successive layers of lucite and lead. Čerenkov radiation emitted in the lucite slabs is collected onto the photocathode of one 5 inch phototube. The geometry as well as the thickness of inserted lead converters can be adapted to kinematical requirements. At 1 BeV/c incoming momentum, the rejection ratio of e, γ showers vs. π or μ is better than 100:1; i.e., proper discrimination setting will allow rejection of 99% of all π's and μ's, while only 1% of e's and γ's will be lost....

  3. Refinements in Bubble Density Measurements

    Fretwell, L. J., Jr.; Coyne, D. G.; Mullins, J. H.

  4. A Study of the Second-Difference Method for Radial Magnet Alignment

    Mathews, Jon
    Preliminary estimates indicate that the cost of surveying the main ring of the proposed 300-BeV cascade synchrotron will be quite high, because of the large diameter (~ 1-1/2 miles) and small tolerances (~ 0.005 inch). Courant and Sands have suggested replacing conventional surveying techniques by a scheme in which the only measurements to be made are local, relating each magnet to its neighbors. In principle, these measurements would enable one to determine the magnet positions (to within an overall translation and/or rotation) much more simply than by conventional techniques. Furthermore, the procedure of measurement and adjustment could be carried out completely...

  5. A 25 Input Pulse Height Recording System

    Marshall, J. H.; Groom, D. E.
    A general description is given of a data recording system which provides a link between counter experiments in high-energy physics and a high-speed digital computer. The instrument described can accept as many as 25 simultaneous photomultiplier tube signals and pulse height analyze them into 100 channels each. Six bits of digital data may be substituted for any unused pulse height input. The usual output is perforated paper tape with a binary coded decimal format for use with a Burroughs 220 computer. Identification words can be set up and recorded on the tape. The speed of the paper tape perforator limits...

  6. A Note on the Leptonic Decays of the K-Meson

    Sharp, David H.; Wagner, William G.
    In this note we present an analysis of the leptonic decay modes of the K-meson in terms of a four-parameter representation of the two form factors F1(q^2) and F3(q^2) which describe the matrix element of the vector current of the weak interactions, < π |Vα| K >. Such a representation, while general enough to take account of the violation of the ΔΙ = 1/2 rule and the possible existence of two resonances in the K-π system, no longer permits unique predictions for the ratio of the electron to muon decay rate, or of the pion spectrum. We therefore suggest that...

  7. K Leptonic Decay and Partially-Conserved Currents

    Zweig, George
    An operational definition for the partial conservation of the strangeness changing vector current is given and applied to leptonic K^+ and K_2^0 decay. The K* resonance is explicitly included in the calculation and quantitative agreement with experiment is obtained. A detailed comparison with the K^+ data of Brown et. al. and Dobbs et. al. is given. Because of rapid variations of a form factor, it is found that the data of these two groups are not in contradiction. From the K_2^0 experiment of Luers et al., I = 1/2 and 3/2 currents are seen to exist. Λβ-decay is briefly considered. It...

  8. Estimating Signaling Games in International Relations: Problems and Solutions

    Crisman-Cox, Casey; Gibilisco, Michael
    Signaling games are central to the study of politics but often have multiple equilibria, leading to no definitive empirical prediction. We demonstrate that these indeterminacies create substantial problems for currently used maximum likelihood techniques: they fail to uncover the parameters of the canonical crisis-signaling game, regardless of sample size, even if the equilibrium in the game generating the data is unique. To overcome this problem, we propose three estimators that outperform current best practices and are well suited to problems in international relations. We fit a signaling model to data on economic sanctions and find that standard maximum likelihood produces...

  9. Sequential Deliberation in Collective Decision-Making: The Case of the FOMC

    López-Moctezuma, Gabriel
    A process of deliberation, in which policymakers exchange information prior to formal voting procedures, precedes almost every collective decision. Yet, beyond scarce evidence coming from field and laboratory experiments, few studies have analyzed the role played by sequential deliberation in policy-relevant decision-making bodies. To fill this gap, I estimate an empirical model of policy-making that incorporates social learning via deliberation. In the model, committee members speak in sequence, allowing them to weight their own information and biases against recommendations made by others. The empirical model is structurally estimated using historical transcripts from the Federal Open Market Committee (FOMC), which is the body...

  10. Policy Deliberation and Voter Persuasion: Experimental Evidence from an Election in the Philippines

    Wantchekon, Leonard; López-Moctezuma, Gabriel; Fujiwara, Thomas; Pe Lero, Cecilia; Rubenson, Daniel
    In a randomized experiment in cooperation with two national parties competing in the 2013 congressional election in the Philippines, we estimate the causal effect on voting behavior of a town-hall style campaign in which candidates discuss their campaign platform with small groups of citizens. Keeping the parties’ platform fixed, we find that this “deliberative” style of campaigning has a positive effect on parties’ vote shares compared to the status quo, in which voters play a passive role. Consistent with the parties’ advocacy for underprivileged groups, we observe heterogeneous effects by income and gender. We show that the larger effect of...

  11. Endogenous Issue Salience in an Ownership Model of Elections

    Ascencio, Sergio; Gibilisco, Michael B.
    We analyze a model of electoral competition based on the issue-ownership theory of campaigns. In the model, parties invest resources to manipulate the salience of various issues, and the salience of an issue is the probability a voter casts her ballot according to her party preferences on that issue. Parties use campaigns to prime voters to think about different issues. Our results uncover Riker’s “dominance principle” and suggest that parties will generally campaign on one issue. The two-dimensional version of the model demonstrates that parties talk past each other and indicates that competition will be most fierce when parties are similarly effective...

  12. Audience Costs and the Dynamics of War and Peace

    Crisman-Cox, Casey; Gibilisco, Michael
    We estimate audience costs and examine their substantive effects on the evolution of interstate disputes by using an infinitely repeated and dynamic game of crisis escalation. Unlike past efforts, our approach estimates country-specific audience cost parameters without replying on proxy variables, e.g., democracy measures. Contrary to intuition, increases in a country's audience costs encourage it to initiate disputes in equilibrium, because the costs serve as a commitment device during the subsequent crisis, incentivizing the country to stand firm and coercing its opponent to back down. Nonetheless, the results demonstrate that larger audience costs would result in more peace worldwide, as they also...

  13. Inefficiencies in the Mexican Peso-U.S. Dollar Exchange Rate Market: Is it Risk Premia or Irrationality?

    López-Moctezuma, Gabriel; San Martín, Andrea
    The efficiency of the peso-dollar exchange rate market is evaluated for the period 1997-2007. Considering the term structure of interest rates, this study finds that the efficient market hypothesis implied in the covered and uncovered interest parity fails to hold for the peso-dollar exchange rate market. With the help of survey data on peso-dollar exchange rate, deviations from efficiency are allocated to a risk premium effect and expectational errors by the method developed by Frankel and Froot (1989). The results from this allocation indicate that the observed departures from efficiency in the peso-dollar exchange market capture both a time-varying risk premium and systematic...

  14. Lecture notes on Turbulent Fluid Motion

    Burgers, J. M.
    Lecture notes of prof. Burgers prepared during his sabbatical at CalTech.

  15. A Testbed Experiment of a (Smart) Marked Based, Student Transportation Policy: Non Convexities, Coordination, Non Existence

    Lee, Hsing Yang; Maron, Travis; Plott, Charles R.; Seo, Han
    The paper develops and studies a decentralized mechanism for pricing and allocation challenges typically met with administrative processes. Traditional forms of markets are not used due to conditions associated with market failure, such as complex coordination problems, thin markets, non-convexities including and zero marginal cost due to lumpy transportation capacities. The mechanism rests on an assignment process that is guided by a computational process, enforces rules and channels information feedback to participants. Special, testbed experimental methods produce high levels of efficiency when confronted by individual behaviors that are consistent with traditional models of strategic behavior.

  16. 4d N=1/2d Yang-Mills Duality in Holography

    Fluder, Martin
    We study the supergravity dual of four-dimensional N=1 superconformal field theories arising from wrapping M5-branes on a K\"ahler two-cycle inside a Calabi-Yau threefold. We derive an effective three-dimensional theory living on the cobordism between the infrared and ultraviolet Riemann surfaces, describing the renormalization group flows between AdS_7 and AdS_5 as well as between different AdS_5 fixed points. The realization of this system as an effective theory is convenient to make connections to known theories, and we show that upon imposing (physical) infrared boundary conditions, the effective three-dimensional theory further reduces to two-dimensional SU(2) Yang-Mills theory on the Riemann surface, thus...

  17. Tick Size, Price Grids and Market Performance: Stable Matches as a Model of Market Dynamics and Equilibrium

    Plott, Charles R.; Roll, Richard; Seo, Han; Zhao, Hao
    This paper reports experiments motivated by ongoing controversies regarding tick size in markets. The minimum tick size in a market dictates discrete values at which bids and asks can be tendered by market participants. All transaction prices must occur at these discrete values, which are established by the rules of each exchange. The simplicity of experiments helps to distinguish among competing models of complex real-world securities markets. We observe patterns predicted by a matching (cooperative game) model. Because a price grid damages the equilibrium of the competitive model, the matching model provides predictions where the competitive model cannot; their predictions...

  18. Mimicking Portfolios

    Roll, Richard; Srivastava, Akshay
    Mimicking portfolios have many applications in the practice of finance. Here, we present a new method for constructing them. We illustrate its application by creating portfolios that mimic individual NYSE stocks. On the construction date, a mimicking portfolio exactly matches its target stock's exposures (betas) to a set of ETFs, which serve as proxies for global factors, and the portfolio has much lower idiosyncratic volatility than its target. Mimicking portfolios require only modest subsequent rebalancing in response to instabilities in target assets and assets used for portfolio construction. Although composed here exclusively of equities, mimicking portfolios show potential for mimicking...

  19. An asteroseismic view of the radius valley: stripped cores, not born rocky

    Van Eylen, V.; Agentoft, Camilla; Lundkvist, M. S.; Kjeldsen, H.; Owen, J. E.; Fulton, B. J.; Petigura, E.; Snellen, I.
    Various theoretical models treating the effect of stellar irradiation on planetary envelopes predict the presence of a radius valley: i.e. a bimodal distribution of planet radii, with super-Earths and sub-Neptune planets separated by a valley at around ≈ 2 R_⊕. Such a valley was observed recently, owing to an improvement in the precision of stellar, and therefore planetary radii. Here we investigate the presence, location and shape of such a valley using a small sample with highly accurate stellar parameters determined from asteroseismology, which includes 117 planets with a median uncertainty on the radius of 3.3%. We detect a clear...

  20. Attaining the 2nd Chargaff Rule by Tandem Duplications

    Jain, Siddharth; Raviv, Netanel; Bruck, Jehoshua
    Erwin Chargaff in 1950 made an experimental observation that the count of A is equal to the count of T and the count of C is equal to the count of G in DNA. This observation played a crucial rule in the discovery of the double stranded helix structure by Watson and Crick. However, this symmetry was also observed in single stranded DNA. This phenomenon was termed as 2nd Chargaff Rule. This symmetry has been verified experimentally in genomes of several different species not only for mononucleotides but also for reverse complement pairs of larger lengths up to a small...

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