119192161
Calibration of the CREAM-I calorimeter
The Cosmic Ray Energetics And Mass (CREAM) calorimeter is designed to measure the spectra of cosmic-ray particles over the energy range from ~10 11 eV to ~10 15 eV. Its first flight as part of the CREAM-I balloon-borne payload in Antarctica during the 2004/05 season resulted in a record- breaking 42 days of exposure. Calorimeter calibration using various beam test data will be discussed in an attempt to assess the uncertainties of the energy measurements.
117761708
Performance of the CREAM calorimeter in accelerator beam test
The CREAM calorimeter, designed to measure the spectra of cosmic-ray nuclei from under 1 TeV to 1000 TeV, is a 20 radiation length (X0) deep sampling calorimeter. The calorimeter is comprised of 20 layers of tungsten interleaved with 20 layers of scintillating fiber ribbons, and is preceded by a pair of graphite interaction targets providing about 0.42 proton interaction lengths (\lambda int). The calorimeter was placed in one of CERN's SPS accelerator beams for calibration and testing. Beams of 150 GeV electrons were used for calibration, and a variety of electron, proton, and nuclear fragment beams were used to test the simulation model of the detector. In this paper we discuss the performance of the calorimeter in the electron beam and compare electron beam data with simulation results.
118519145
Design and construction of a Cherenkov imager for charge measurement of nuclear cosmic rays
A proximity focusing Cherenkov imager called CHERCAM, has been built for the charge measurement of nuclear cosmic rays with the CREAM instrument. It consists of a silica aerogel radiator plane across from a detector plane equipped with 1,600 1`` diameter photomultipliers. The two planes are separated by a ring expansion gap. The Cherenkov light yield is proportional to the charge squared of the incident particle. The expected relative light collection accuracy is in the few percents range. It leads to an expected single element separation over the range of nuclear charge Z of main interest 1 ? Z26. CHERCAM is designed to fly with the CREAM balloon experiment. The design of the instrument and the implemented technical solutions allowing its safe operation in high altitude conditions (radiations, low pressure, cold) are presented.
115533125
Next generation TRD for CREAM using gas straw tubes and foam radiators
The Cosmic Ray Energetics And Mass (CREAM) experiment is designed to investigate the source, propagation and acceleration mechanism of high energy cosmic-ray nuclei, by directly measuring their energy and charge. Incorporating a transition radiation detector (TRD) provides an energy measurement complementary to the calorimeter, as well as additional track reconstruction capability. The next generation CREAM TRD is designed with 4 mm straw tubes to greatly improve tracking over the previous 20 mm tube design, thereby enhancing charge identification in the silicon charge detector (SCD). Plastic foam provides a weight-efficient radiator that doubles as a mechanical support for the straw layers. This design provides a compact, robust, reliable, low density detector to measure incident nucleus energy for 3 < Z < 30 nuclei in the Lorentz gamma factor range of 10 10. This paper discusses the new TRD design and the low power front end electronics used to achieve the large dynamic range required. Beam test results of a prototype TRD are also reported.
180594919
STATUS AND RECENT RESULTS FROM THE CREAM EXPERIMENT
14404026
CHERCAM: The Cherenkov imager of the CREAM experiment
A Cherenkov imager, CHERCAM (CHERenkov CAMera), has been designed and built for the CREAM (Cosmic-Ray Energetic and Mass) balloon-borne experiment. The instrument will perform charge measurements of nuclear cosmic-ray over a range extending from proton to iron. It will achieve individual charge separation of the elements over this range [M. Buenerd, et al., in: 28th ICRC, Tsukuba, Japan, OG 1.5, 2003, p. 2157. [2]] (0:25 charge unit rms), allowing measurements of the energy spectra of individual elements by the CREAM instrument in the energy range from 1010 to 1015 eV. CHERCAM is a proximity focused imager, based on a dedicated mechanical structure, equipped with an n ¼ 1:05 silica aerogel radiator plane, separated by a 12 cm ring expansion gap from a photon detector plane consisting of a 1600 photomultiplier array, backed with dedicated front-end readout electronics. A prototype of the detector has been recently tested with 100 and 300 GeV/c Z ¼ 1 particle beams at CERN. The contribution reports on both the beam test results of the prototype, and of the counter performance in ground operation.
119237348
Problems with Mannheim’s conformal gravity program
We show that Mannheim's conformal gravity program, whose potential has a term proportional to $1/r$ and another term proportional to $r$, does not reduce to Newtonian gravity at short distances, unless one assumes undesirable singularities of the mass density of the proton. Therefore, despite the claim that it successfully explains galaxy rotation curves, unless one assumes the singularities, it seems to be falsified by numerous Cavendish-type experiments performed at laboratories on Earth whose work have not found any deviations from Newton's theory. Moreover, it can be shown that as long as the total mass of the proton is positive, Mannheim's conformal gravity program leads to negative linear potential, which is problematic from the point of view of fitting galaxy rotation curves, which necessarily requires positive linear potential.
118678608
Quantum corrections to the Hawking radiation spectrum
In 1995, Bekenstein and Mukhanov suggested that the Hawking radiation spectrum was discrete if the area spectrum was quantized in such a way that the allowed areas were integer multiples of a single unit area. However, in 1996, Barreira, Carfora, and Rovelli argued that the Hawking radiation spectrum was continuous if the area spectrum was quantized with an infinite number of unit areas, as predicted by loop quantum gravity, rather than quantized with the single unit area considered by Bekenstein and Mukhanov. In this paper, contrary to what Barreira, Carfora, and Rovelli argued, we show that the Hawking radiation spectrum is still discrete when the area spectrum is quantized as loop quantum gravity predicts. In particular, we show that, for a black hole of a given temperature, the Hawking radiation spectrum is truncated at frequencies below a certain frequency.
116926585
Third potential evidence for the new area spectrum based on the Einstein-Kaufman pseudo tensor, a conjecture
This paper has been withdrawn by the authors. In our earlier paper "Corrections to the Bekenstein-Hawking entropy and the Hawking radiation spectrum", arXiv:0910.2755, we provided two concrete numerical evidences for the new area spectrum based on the Einstein-Kaufman pseudo tensor as opposed to the Ashtekar variables: namely, the reproduction of the Bekenstein-Hawking entropy without fixing Immirzi parameter and the reproduction of the Hawking radiation spectrum. In this article, we provide another potential, albeit not concrete, numerical evidence for this new area spectrum; there was a constant in our earlier article, which was inversely proportional to the density of state, and which we could not fix a priori. Nevertheless, in our earlier article, we obtained this constant to be around 172$\sim$173 by fitting it to the Planck radiation spectrum. In this article, we propose a mathematical formula that reproduces this value. According to this formula, this constant is around 172.8. Nevertheless, we failed to concretely derive this mathematical formula. Therefore, it is a conjecture.
118611210
Approximation of the naive black hole degeneracy
In 1996, Rovelli suggested a connection between black hole entropy and the area spectrum. Using this formalism and a theorem we prove in this paper, we briefly show the procedure to calculate the quantum corrections to the Bekenstein–Hawking entropy. One can do this by two steps. First, one can calculate the “naive” black hole degeneracy without the projection constraint (in case of the $$U(1)$$ symmetry reduced framework) or the $$SU(2)$$ invariant subspace constraint (in case of the fully $$SU(2)$$ framework). Second, then one can impose the projection constraint or the $$SU(2)$$ invariant subspace constraint, obtaining logarithmic corrections to the Bekenstein–Hawking entropy. In this paper, we focus on the first step and show that we obtain infinite relations between the area spectrum and the naive black hole degeneracy. Promoting the naive black hole degeneracy into its approximation, we obtain the full solution to the infinite relations.