119928689
A measurement of the inclusive cross section of charged pions at very high transverse momenta
Abstract The inclusive cross sections for the production of high transverse momentum π + and π − mesons in proton-proton interactions have been measured at the highest ISR energy √ s = 63 GeV and at a c.m. production angle of 50°. The cross sections for π + and π − mesons are compared as a function of transverse momentum. It is shown that the inclusive cross section of π − mesons decreases faster than the π + cross section. particle σ ( π ± )/ σ (charged particles) are presented as a function of transverse momentum.
120405256
Direct search for light gluinos
Abstract We present the results for a direct search for light gluinos through the appearance of η →3 π 0 with high transverse momentum in the vacuum tank of the NA48 experiment at CERN. We find one event within a lifetime range of 10 −9 –10 −3 s and another one between 10 −10 –10 −9 s. Both events are consistent with the expected background from neutrons in the beam, produced by 450 GeV protons impinging on the Be targets, which interact with the residual air in the tank. From these data we give limits on the production of the hypothetical g g bound state, the R 0 hadron, and its R 0 →η γ decay in the R 0 mass range between 1 and 5 GeV.
116379925
RECENT RESULTS FROM THE UA1 COLLABORATION AT THE CERN PROTON - ANTI-PROTON COLLIDER
121957172
A system of multigap proportional wire chambers
Abstract A set of proportional chambers has been constructed for a multiparticle spectrometer at the CERN Intersecting Storage Rings (ISR). The detector consists of 73 000 wires and covers an effective area of 300 m 2 . In this paper we will describe the design and performance of this detector.
122552269
PERFORMANCE OF AN ELECTROMAGNETIC LIQUID KRYPTON CALORIMETER
Abstract A prototype electromagnetic calorimeter containing 180 litres of liquid krypton has been tested in electron and muon beams at the CERN SPS. The main features of this detector are its active shower medium, a granularity of 2 cm with tower readout, and the use of the initial current readout technique with an effective shaping time of about 60 ns. An energy resolution for electrons of 4.1% √E[ GeV ] with a constant term of 0.4% and a noise contribution of 50 MeV has been achieved. The calorimeter has a spatial resolution of 4.5 mm √E[ GeV ] with a constant term of 0.3 mm and a time resolution of about 0.5 ns for energies larger than 10 GeV.
125139127
Proposal to measure the rare decay K+ ---> pi+ nu anti-nu at the CERN SPS
119279122
Recovering Joy’s Law as a Function of Solar Cycle, Hemisphere, and Longitude
Bipolar active regions in both hemispheres tend to be tilted with respect to the East–West Equator of the Sun in accordance with Joy’s law, which describes the average tilt angle as a function of latitude. Mt. Wilson Observatory data from 1917 – 1985 are used to analyze the active-region tilt angle as a function of solar cycle, hemisphere, and longitude, in addition to the more common dependence on latitude. Our main results are as follows: i) We recommend a revision of Joy’s law towards a weaker dependence on latitude (slope of 0.13 – 0.26) and without forcing the tilt to zero at the Equator. ii) We determine that the hemispheric mean tilt value of active regions varies with each solar cycle, although the noise from a stochastic process dominates and does not allow for a determination of the slope of Joy’s law on an 11-year time scale. iii) The hemispheric difference in mean tilt angles, 1.1∘±0.27, over Cycles 16 to 21 was significant to a three-σ level, with average tilt angles in the Northern and Southern hemispheres of 4.7∘±0.26 and 3.6∘±0.27, respectively. iv) Area-weighted mean tilt angles normalized by latitude for Cycles 15 to 21 anticorrelate with cycle strength for the southern hemisphere and whole-Sun data, confirming previous results by Dasi-Espuig et al. (Astron. Astrophys.518, A7, 2010). The Northern Hemispheric mean tilt angles do not show a dependence on cycle strength. v) Mean tilt angles do not show a dependence on longitude for any hemisphere or cycle. In addition, the standard deviation of the mean tilt is 29 – 31∘ for all cycles and hemispheres, indicating that the scatter is due to the same consistent process even if the mean tilt angles vary.
53608040
Characteristics of Magnetohydrodynamic Oscillations Observed with the Michelson Doppler Imager
We report on the spatial distribution of the magnetogram oscillatory power and the phase angles between velocity and magnetogram signals as observed with the Michelson Doppler Imager. The data set is 15125 × 15125, containing the sunspot from 1997 December 2 with a temporal sampling interval of 60 s and spatial sampling of 0605. The simultaneously observed continuum intensity and surface velocity accompany the magnetic information. We focus on three frequency regimes: 0.5-1.0, 3.0-3.5, and 5.5-6.0 mHz, corresponding roughly to timescales of magnetic evolution, p-modes, and the 3 minute resonant sunspot oscillation. Significant low-frequency magnetogram power is found in lower flux pixels, 100-300 G, in a striking ring with filamentary structure surrounding the sunspot. The 5 minute magnetogram power peaks in extended regions of flux that measure 600-800 G. The 3 minute oscillation is observed in the sunspot umbra in pixels whose flux measures 1300-1500 G. Phase angles of approximately -90° between velocity and magnetic flux in the 3.0-3.5 and 5.5-6.0 mHz regimes are found in regions of significant cross amplitude.
118533577
Solar-Cycle Characteristics Examined in Separate Hemispheres: Phase, Gnevyshev Gap, and Length of Minimum
According to research results from solar-dynamo models, the northern and southern hemispheres may evolve separately throughout the solar cycle. The observed phase lag between the northern and southern hemispheres provides information regarding how strongly the hemispheres are coupled. Using hemispheric sunspot-area and sunspot-number data from Cycles 12 – 23, we determine how out of phase the separate hemispheres are during the rising, maximum, and declining period of each solar cycle. Hemispheric phase differences range from 0 – 11, 0 – 14, and 2 – 19 months for the rising, maximum, and declining periods, respectively. The phases appear randomly distributed between zero months (in phase) and half of the rise (or decline) time of the solar cycle. An analysis of the sunspot cycle double peak, or Gnevyshev gap, is conducted to determine if the double-peak is caused by the averaging of two hemispheres that are out of phase. We confirm previous findings that the Gnevyshev gap is a phenomenon that occurs in the separate hemispheres and is not due to a superposition of sunspot indices from hemispheres slightly out of phase. Cross hemispheric coupling could be strongest at solar minimum, when there are large quantities of magnetic flux at the Equator. We search for a correlation between the hemispheric phase difference near the end of the solar cycle and the length of solar-cycle minimum, but found none. Because magnetic flux diffusion across the Equator is a mechanism by which the hemispheres couple, we measured the magnetic flux crossing the Equator by examining Kitt Peak Vacuum Telescope and SOLIS magnetograms for Solar Cycles 21 – 23. We find, on average, a surplus of northern hemisphere magnetic flux crossing during the mid-declining phase of each solar cycle. However, we find no correlation between magnitude of magnetic flux crossing the Equator, length of solar minima, and phase lag between the hemispheres.
119207648
SOLIS vector spectromagnetograph: status and science
The Vector Spectromagnetograph (VSM) instrument has recorded photospheric and chromospheric magnetograms daily since August 2003. Full-disk photospheric vector magnetograms are observed at least weekly and, since November 2006, area-scans of active regions daily. Quick-look vector magnetic images, plus X3D and FITS formated files, are now publicly available daily. In the near future, Milne-Eddington inversion parameter data will also be available and a typical observing day will include three full-disk photospheric vector magnetograms. Besides full-disk observations, the VSM is capable of high temporal cadence area-scans of both the photosphere and chromosphere. Carrington rotation and daily synoptic maps are also available from the photospheric magnetograms and coronal hole estimate images.