214 research outputs found
Evaluation of a High-Power Target Design for Positron Production at CEBAF
A source for polarized positron beams at the Continuous Electron Beam
Accelerator Facility (CEBAF) at Jefferson Lab is being designed. The Polarized
Electrons for Polarized Positrons (PEPPo) concept is used to produce polarized
ee-pairs from the bremsstrahlung radiation of a longitudinally
polarized electron beam interacting within a high- conversion target. The
scheme under consideration includes a 4 mm thick tungsten target that absorbs
17 kW deposited by a 1 mA continuous-wave electron beam with an energy of 120
MeV. The concept of a rotating tungsten rim mounted on a water-cooled copper
disk was explored. The results of ANSYS thermal and mechanical analyses are
discussed together with FLUKA evaluations of the radiation damages.Comment: 14th International Particle Accelerator Conference (IPAC'23
Information and the dispersion of cross-border equity holdings
This paper studies, both theoretically and empirically, dispersion in cross-border equity holdings. We present a multi-asset rational expectations equilibrium model in which agents have information about asset-specific components of payoff and/or information about components that affect many stocks' payoffs.Information economics ; REE Models
Double Exponential Instability of Triangular Arbitrage Systems
If financial markets displayed the informational efficiency postulated in the
efficient markets hypothesis (EMH), arbitrage operations would be
self-extinguishing. The present paper considers arbitrage sequences in foreign
exchange (FX) markets, in which trading platforms and information are
fragmented. In Kozyakin et al. (2010) and Cross et al. (2012) it was shown that
sequences of triangular arbitrage operations in FX markets containing 4
currencies and trader-arbitrageurs tend to display periodicity or grow
exponentially rather than being self-extinguishing. This paper extends the
analysis to 5 or higher-order currency worlds. The key findings are that in a
5-currency world arbitrage sequences may also follow an exponential law as well
as display periodicity, but that in higher-order currency worlds a double
exponential law may additionally apply. There is an "inheritance of
instability" in the higher-order currency worlds. Profitable arbitrage
operations are thus endemic rather that displaying the self-extinguishing
properties implied by the EMH.Comment: 22 pages, 22 bibliography references, expanded Introduction and
Conclusion, added bibliohraphy reference
The Strange Quark Contribution to the Proton's Magnetic Moment
We report a new determination of the strange quark contribution to the
proton's magnetic form factor at a four-momentum transfer Q2 = 0.1 (GeV/c)^2
from parity-violating e-p elastic scattering. The result uses a revised
analysis of data from the SAMPLE experiment which was carried out at the
MIT-Bates Laboratory. The data are combined with a calculation of the proton's
axial form factor GAe to determine the strange form factor GMs(Q2=0.1)=0.37 +-
0.20 +- 0.26 +- 0.07. The extrapolation of GMs to its Q2=0 limit and comparison
with calculations is also discussed.Comment: 6 pages, 1 figure, submitted to Phys. Lett.
Transverse Beam Spin Asymmetries in Forward-Angle Elastic Electron-Proton Scattering
We have measured the beam-normal single-spin asymmetry in elastic scattering of transversely polarized 3 GeV electrons from unpolarized protons at Q^2=0.15, 0.25ââ(GeV/c)^2. The results are inconsistent with calculations solely using the elastic nucleon intermediate state and generally agree with calculations with significant inelastic hadronic intermediate state contributions. A_n provides a direct probe of the imaginary component of the 2Îł exchange amplitude, the complete description of which is important in the interpretation of data from precision electron-scattering experiments
Parity Violation in Elastic Electron-Proton Scattering and the Proton's Strange Magnetic Form Factor
We report a new measurement of the parity-violating asymmetry in elastic electron scattering from the proton at backward scattering angles. This asymmetry is sensitive to the strange magnetic form factor of the proton as well as electroweak axial radiative corrections. The new measurement of A = -4.92±0.61±0.73 ppm provides a significant constraint on these quantities. The implications for the strange magnetic form factor are discussed in the context of theoretical estimates for the axial corrections
Parity-violating Electron Deuteron Scattering and the Proton's Neutral Weak Axial Vector Form Factor
We report on a new measurement of the parity-violating asymmetry in
quasielastic electron scattering from the deuteron at backward angles at Q2=
0.038 (GeV/c)2. This quantity provides a determination of the neutral weak
axial vector form factor of the nucleon, which can potentially receive large
electroweak corrections. The measured asymmetry A=-3.51 +/- 0.57(stat) +/-
0.58(sys)ppm is consistent with theoretical predictions. We also report on
updated results of the previous experiment at Q2=0.091 (GeV/c)2, which are also
consistent with theoretical predictions.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let
Parity-violating Electron Deuteron Scattering and the Proton's Neutral Weak Axial Vector Form Factor
We report on a new measurement of the parity-violating asymmetry in
quasielastic electron scattering from the deuteron at backward angles at Q2=
0.038 (GeV/c)2. This quantity provides a determination of the neutral weak
axial vector form factor of the nucleon, which can potentially receive large
electroweak corrections. The measured asymmetry A=-3.51 +/- 0.57(stat) +/-
0.58(sys)ppm is consistent with theoretical predictions. We also report on
updated results of the previous experiment at Q2=0.091 (GeV/c)2, which are also
consistent with theoretical predictions.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let
Parity Violation in Elastic Electron-Proton Scattering and the Proton's Strange Magnetic Form Factor
We report a new measurement of the parity-violating asymmetry in elastic
electron scattering from the proton at backward scattering angles. This
asymmetry is sensitive to the strange magnetic form factor of the proton as
well as electroweak axial radiative corrections. The new measurement of A=-4.92
+- 0.61 +- 0.73 ppm provides a significant constraint on these quantities. The
implications for the strange magnetic form factor are discussed in the context
of theoretical estimates for the axial corrections.Comment: 4 pages, 3 figures, submitted to Physical Review Letters, Sept 199
Measurement of the vector analyzing power in elastic electron-proton scattering as a probe of double photon exchange amplitudes
We report the first measurement of the vector analyzing power in inclusive
transversely polarized elastic electron-proton scattering at Q^2 = 0.1
(GeV/c)^2 and large scattering angles. This quantity should vanish in the
single virtual photon exchange, plane wave impulse approximation for this
reaction, and can therefore provide information on double photon exchange
amplitudes for electromagnetic interactions with hadronic systems. We find a
non-zero value of A=-15.4+/-5.4 ppm. No calculations of this observable for
nuclei other than spin 0 have been carried out in these kinematics, and the
calculation using the spin orbit interaction from a charged point nucleus of
spin 0 cannot describe these data.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let
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