Recursos de colección
Caltech Authors (142.336 recursos)
Repository of works by Caltech published authors.
Status = Unpublished
Repository of works by Caltech published authors.
Status = Unpublished
Ruderman, H.; Gomez, R.; Tollestrup, A. V.
Two identical large lead glass shower detectors, or Cerenkov counters, have been built to detect and measure the energies of decay photons from neutral pions. This method of detecting high energy gamma rays has the advantage of 100 percent efficiency, good energy resolution, linearity of response, insensitivity to heavy charged particles, and short time resolution. In addition, the physical size of the detector need only increase logarithmically with the energy of the incident particle to preserve linearity and resolution.
Mullins, J. H.
The following is an analytic investigation, using first order theory only, of a proposed achromatic inflector for the Caltech Synchrotron. Nothing new in principle is involved in any of the theory presented below, and similar types of analyses have been carried out by others). The investigation was prompted by the need to find a specific achromatic inflector to couple a 10 MeV electron linac to the Caltech synchrotron. In particular, it was desired to find a system such that the injector was placed in a convenient location, and, if any electrostatic elements were used, that they have reasonably low required...
Watson, Keith R.; Hankins, Denis
Recent theoretical investigations of high energy nucleon-nucleon collisions support the two-center model of multiple meson production as discussed by Ciok, et al. To facilitate a prediction of the most probable distribution of shower particles as a function of laboratory energy, Farley's kinematical treatment of the "two-fireball" model is employed. A statistical determination of the multiplicity of pion (including neutrals) production per collision is assumed to be valid with possible corrections suggested through restrictions imposed by experimental values of the inelasticity, Κ_π.
Glashow, Sheldon L.; Gell-Mann, Murray
The possibility of generalizing the Yang-Mills trick is examined. Thus we seek theories of vector bosons invariant under continuous groups of coordinate-dependent linear transformations. All such theories may be expressed as superpositions of certain "simple" theories; we show that each "simple" theory is associated with a simple Lie algebra. We may introduce mass terms for the vector bosons at the price of destroying the gauge-invariance for coordinate-dependent gauge functions. The theories corresponding to three particular simple Lie algebras — those which admit precisely two commuting quantum num- bers — are examined in some detail as examples. One of them might play...
Evans, A. S.; Scoville, N. Z.; Dinshaw, N.; Armus, L.; Soifer, B. T.; Neugebauer, G.; Rieke, M.
High-resolution, 1.10, 2.05, 2.12, and 2.15 μm imaging of the gravitationally lensed system FSC10214+4724 are presented. These data extend Hubble Space Telescope (HST) observations of the lens system to redder wavelengths, thus providing the highest resolution images to date of the rest-frame optical and narrow-line (i.e., Hɑ+[N II]) regions of the background quasar. The length of the arc in the wide-band continuum images increases with increasing wavelength, and the Hɑ+[N II] emission has a length in between that of the 1.10 and 2.05 μm. The structure of the arc changes from having an eastern and western peak at 1.10 μm to...
Tropp, Joel A.; Yurtsever, Alp; Udell, Madeleine; Cevher, Volkan
This paper develops a suite of algorithms for constructing low-rank approximations of an input matrix from a random linear image of the matrix, called a sketch. These methods can preserve structural properties of the input matrix, such as positive-semidefiniteness, and they can produce approximations with a user-specified rank. The algorithms are simple, accurate, numerically stable, and provably correct. Moreover, each method is accompanied by an informative error bound that allows users to select parameters a priori to achieve a given approximation quality. These claims are supported by computer experiments.
Bahramian, Arash; Heinke, Craig O.; Tudor, Vlad; Miller-Jones, James C. A.; Bogdanov, Slavko; Maccarone, Thomas J.; Knigge, Christian; Sivakoff, Gregory R.; Chomiuk, Laura; Strader, Jay; García, Javier A.; Kallman, Timothy
47 Tuc X9 is a low mass X-ray binary (LMXB) in the globular cluster 47 Tucanae, and was previously thought to be a cataclysmic variable. However, Miller-Jones et al. (2015) recently identified a radio counterpart to X9 (inferring a radio/X-ray luminosity ratio consistent with black hole LMXBs), and suggested that the donor star might be a white dwarf. We report simultaneous observations of X9 performed by Chandra, Nustar and Australia Telescope Compact Array. We find a clear 28.18$\pm$0.02 min periodic modulation in the Chandra data, which we identify as the orbital period, confirming this system as an ultracompact X-ray binary. Our X-ray spectral fitting provides evidence for photoionized gas...
Peterson, Vincent Z.
This report is an examination of the principal characteristics of a vacuum system for the proposed 300 Bev cascade synchrotron 1). In par- ticular, we wish to see whether the small aperture and large circumference of the Main Ring present vacuum difficulties. Gas scattering losses, eddy currents in the vacuum chamber wall, and cost of a 5-mile vacuum system are of special interest. Attention has been directed primarily toward the Main Ring. The 10 Gev Booster Ring 1) has vacuum requirements similar to existing accelerators, and it is presumed that duplication or modification of such vacuum systems will be practical. Our...
Yaron, O.; Perley, D. A.; Gal-Yam, A.; Groh, J. H.; Horesh, A.; Ofek, E. O.; Kulkarni, S. R.; Sollerman, J.; Fransson, C.; Rubin, A.; Szabo, P.; Sapir, N.; Taddia, F.; Cenko, S. B.; Valenti, S.; Arcavi, I.; Howell, D. A.; Kasliwal, M. M.; Vreeswijk, P. M.; Khazov, D.; Fox, O. D.; Cao, Y.; Gnat, O.; Kelly, P. L.; Nugent, P. E.; Filippenko, A. V.; Laher, R. R.; Wozniak, P. R.; Lee, W. H.; Rebbapragada, U. D.; Maguire, K.; Sullivan, M.; Soumagnac, M. T.
With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, that sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF13dqy = SN 2013fs, a mere ~3 hr after explosion. Our rapid follow-up observations, which include multiwavelength photometry and extremely early (beginning at ~6 hr post-explosion) spectra, map the distribution of material in the immediate environment (≾ 10^(15) cm) of the...
Peretsman-Clement, Gail; Wrublewski, Donna
Today's researchers are challenged to master an ever-expanding and interlinked set of information and publishing skills in the rapidly evolving scholarly web. An emerging approach, called carpentry, teaches researchers at all career stages best practices and efficient tools for handling, sharing, publishing, and providing fair attribution for research outputs of all types: data, software, and papers. The ultimate aim of software, data and author carpentry is to support more open, transparent, and reusable research to advance and strengthen science in the digital era. This workshop will introduce you to principles of carpentry, teach you a carpentry module on examining, cleaning,...
Barna, Arpad; Marshall, Howard J.
A distributed amplifier with a stable gain of 10, risetime of 2.5 nanoseconds for 125 ohm load impedance is described. The maximum output voltage is 3.2 volts with negative polarity. The amplifier consists of 2 stages of 6 Philco 2N1742 transistors each and an emitter follower using a 2N1500. Design formulae are derived and detailed performance of a specific amplifier is given.
The purpose of this note is to study the effects on betatron frequencies -- in particular, their variation with particle energy — due to non-linear magnet fields. The idea is to determine whether non- linearities can be introduced deliberately in such a way that ν, the number of betatron wavelengths in the circumference, is independent of particle energy for energies near the equilibrium energy. The result is that non-linearities of a magnitude such that the field index n varies by about 1 per cent per cm will suffice.
Fredrickson, Laura; Pei, Du; Yan, Wenbin; Ye, Ke
We use Coulomb branch indices of Argyres-Douglas theories on S1×L(k,1) to quantize moduli spaces M_H of wild/irregular Hitchin systems. In particular, we obtain formulae for the "wild Hitchin characters" -- the graded dimensions of the Hilbert spaces from quantization -- for four infinite families of M_H, giving access to many interesting geometric and topological data of these moduli spaces. We observe that the wild Hitchin characters can always be written as a sum over fixed points in M_H under the U(1) Hitchin action, and a limit of them can be identified with matrix elements of the modular transform STkS in...
Shenker, Jacob Quinn
David Liu’s group developed a technique they call Phage-Assisted Continuous Evolution (PACE) for doing directed evolution of proteins by coupling the desired activity of the protein of interest to the production of protein III, which controls the infectiousness of M13 phage. Because they can evolve a large (1011) phage population for a few days or a week with little manual intervention, they have been able to achieve much faster evolution than other directed evolution approaches.
Design of transistor circuits, particularly those operating in the nanosecond time range necessitated the measurement of some transistor parameters usually not specified by the manufacturers. Collector to base capacitance, gain-bandwidth product, beta and base spreading resistance of the transistors of Table 1 were measured.
Jain, Siddharth; Farnoud (Hassanzadeh), Farzad; Schwartz, Moshe; Bruck, Jehoshua
Duplication mutations play a critical role in the generation of biological sequences. Simultaneously, they have a deleterious effect on data stored using in-vivo DNA data storage. While duplications have been studied both as a sequence-generation mechanism and in the context of error correction, for simplicity these studies have not taken into account the presence of other types of mutations. In this work, we consider the capacity of duplication mutations in the presence of point-mutation noise, and so quantify the generation power of these mutations. We show that if the number of point mutations is vanishingly small compared to the number of duplication mutations...
Transient responses, input and output impedances have been derived for the use of the circuit designer. A hybrid equivalent circuit was assumed to be correct and has been used as the basis of the derived relationships. Grounded emitter, grounded base, grounded collector and emitter degenerated configurations are discussed.
Tollestrup, A. V.
If a low energy synchrotron is to be used as an injector for a 300 Bev machine, the problem may arise of synchronizing the two R.F. systems at transfer time in order that a bunch of protons in the injector may be transferred to a bucket in the main machine without loss of particles. A possible synchronization scheme is proposed and investigated here.
Gell-Mann, Murray; Zachariasen, Fredrik
There is no question that broken symmetries are of the highest importance in particle physics. We are familiar with the conservation of the isotopic spin current, which is violated by electromagnetism, and the conservation of the strangeness or hypercharge current, which is violated by the weak interactions. In both of these cases, the violations are small.