Data acquisition system for phase-2 KGF proton decay experiment

Phase-2 of KGF proton decay experiment using 4000 proportional counters will start operating from middle of 1985. The detection systems, in addition to measuring the time information to an accuracy of 200 n see, also records ionization in the hit counters. It also monitors different characteristics of the counters like pulse height spectrum, pulse width spectrum and counting rate. The acquisition system is discussed

Results on nucleon life-time from the Kolar gold field experiment

The KGF nucleon decay experiment has been in operation since October 1980 with a 140 ton calorimetric detector at a depth of 2.3 Km underground. The detector comprises 34 layers of proportional counters arranged in an orthogonal geometry with 12 mm thick iron plates in between successive layers. The proportional counters are made up of square (10 x 10 square centimeters) iron plates of wall thickness 2.3 mm. Each of the 1600 counters is instrumented to provide data on ionization, DE/dx and arrival time. The visible energy of a particle is determined to an accuracy of approximately 20% from the ionization and range of its track. The end point ionization of a stopping track provides the direction of motion as well as the nature of the particle (mu/pi,k,p). Decay of mu is recorded with an overall efficiency of only 20% in view of the thickness of 13 g/square centimeters between successive layers

Muon and neutrino results from KGF experiment at a depth of 7000 hg/square cm

The KGF nucleon decay experiment at a depth of 7000 hg/sq cm has provided valuable data on muons and neutrinos. The detector comprised of 34 crossed layers of proportional counters (cross section 10 x 10 sq cm; lengths 4m and 6m) sandwiched between 1.2 cm thick iron plates can record tracks of charged particles to an accuracy of 1 deg from tracks that traverse the whole of the detector. A special two-fold coincidence system enables the detector to record charged particles that enter at very large zenith angles. In a live time of 3.6 years about 2600 events have been recorded. These events include atmospheric muons, neutrino induced muons from rock, stopping muons, showers and events which have their production vertex inside the detectors. The results on atmospheric muons and neutrino events are presented

Radiative forcing by aerosols over the Bay of Bengal region derived from shipborne, island-based, and satellite (moderate-resolution imaging spectroradiometer) observations

Measurements of spectral aerosol optical depths (AODs) were made over the Bay of Bengal region (adjacent to the Indian landmass) on board the oceanographic research vessel Sagar Kanya during February 2003. Simultaneous measurements of spectral AODs and mass concentrations of the composite aerosols and aerosol black carbon (BC) were made at an island location, Port Blair (11.63°N, 92.71°E), also in the Bay of Bengal. At the cruise locations the AODs were in the range of ~0.3-0.6 at 500 nm (with a mean value of 0.41 ± 0.14) and Angstrom wavelength exponent of ~1.1 ± 0.1; while at Port Blair the AODs were in the range of 0.11-0.48 at 500 nm and Angstrom wavelength exponent of 0.98 ± 0.07. Aerosol BC constituted 5.8 ± 0.6% of the composite aerosol mass concentration with a single-scattering albedo of ~0.88, indicating the presence of a significant amount of submicron absorbing aerosols. Comparisons of AODs measured at Port Blair during cruise 188 and an earlier cruise (cruise 161B) during March 2001 (over the Bay of Bengal, Arabian Sea, and Indian Ocean) with those derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) (on board the TERRA platform) showed excellent agreement with a mean difference of ~0.01 and a root-meansquare difference of ~0.03. Regionally averaged aerosol (net) forcing over the Bay of Bengal was in the range -15 to -24 W m-2 at the surface and -2 to -4 W m-2 at the top of the atmosphere in February 2003; these values were smaller in magnitude than those observed over this region during March 2001 and larger than that observed over the Arabian Sea and the Indian Ocean. The resulting atmospheric heating due to aerosol absorption was ~0.5°K/d

Effect of cryogenic grinding on fatigue life of additively manufactured maraging steel

Additive manufacturing (AM) is replacing conventional manufacturing techniques due to its ability to manufacture complex structures with near-net shape and reduced material wastage. However, the poor surface integrity of the AM parts deteriorates the service life of the components. The AM parts should be subjected to post-processing treatment for improving surface integrity and fatigue life. In this research, maraging steel is printed using direct metal laser sintering (DMLS) process and the influence of grinding on the fatigue life of this additively manufactured material was investigated. For this purpose, the grinding experiments were performed under two different grinding environments such as dry and cryogenic conditions using a cubic boron nitride (CBN) grinding wheel. The results revealed that surface roughness could be reduced by about 87% under cryogenic condition over dry grinding. The fatigue tests carried out on the additive manufactured materials exposed a substantial increase of about 170% in their fatigue life when subjected to cryogenic grinding

Scattering phase Function Spectrum Makes Reflectance Spectrum Measured from Intralipid phantoms and Tissue Sensitive to the Device Detection Geometry

Reflectance spectra measured in Intralipid (IL) close to the source are sensitive to wavelength -dependent changes in reduced scattering coefficient (μs′)and scattering phase function (PF). Experiments and simulations were performed using device designs with either single or separate optical fibers for delivery and collection of light in varying concentrations of IL. Spectral reflectance is not consistentl y linear with varying IL concentration, with PF -dependent effects observed for single fiber devices with diameters smaller than ten transport lengths and for separate source- detector devices that collected light at less than half of a transport length from the source. Similar effects are thought to be seen in tissue, limiting the ability to quantitatively compare spectra from different devices without compensation

Scattering phase function spectrum makes reflectance spectrum measured from Intralipid phantoms and tissue sensitive to the device detection geometry

Reflectance spectra measured in Intralipid (IL) close to the source are sensitive to wavelength-dependent changes in reduced scattering coefficient (μ′s) and scattering phase function (PF). Experiments and simulations were performed using device designs with either single or separate optical fibers for delivery and collection of light in varying concentrations of IL. Spectral reflectance is not consistently linear with varying IL concentration, with PF-dependent effects observed for single fiber devices with diameters smaller than ten transport lengths and for separate source-detector devices that collected light at less than half of a transport length from the source. Similar effects are thought to be seen in tissue, limiting the ability to quantitatively compare spectra from different devices without compensation

Atmospheric Muon Flux at Sea Level, Underground, and Underwater

The vertical sea-level muon spectrum at energies above 1 GeV and the underground/underwater muon intensities at depths up to 18 km w.e. are calculated. The results are particularly collated with a great body of the ground-level, underground, and underwater muon data. In the hadron-cascade calculations, the growth with energy of inelastic cross sections and pion, kaon, and nucleon generation in pion-nucleus collisions are taken into account. For evaluating the prompt muon contribution to the muon flux, we apply two phenomenological approaches to the charm production problem: the recombination quark-parton model and the quark-gluon string model. To solve the muon transport equation at large depths of homogeneous medium, a semi-analytical method is used. The simple fitting formulas describing our numerical results are given. Our analysis shows that, at depths up to 6-7 km w. e., essentially all underground data on the muon intensity correlate with each other and with predicted depth-intensity relation for conventional muons to within 10%. However, the high-energy sea-level data as well as the data at large depths are contradictory and cannot be quantitatively decribed by a single nuclear-cascade model.Comment: 47 pages, REVTeX, 15 EPS figures included; recent experimental data and references added, typos correcte

Cosmic ray muons at a depth of 754 hg/cm<SUP>2</SUP> in the Kolar Gold Mines

A telescope of area 4 m2, consisting of horizontal layers of plastic scintillators, neon flash tubes and absorbers was operated at a depth of 754 hg/cm2 in the Kolar Gold Mines. New values for the vertical intensities of muons have been obtained from observations of the angular distribution over the slant depths ~750-2300 hg/cm2 and are compared with the existing measurements. From the angular distribution observed, we conclude that muons are produced wholly through the decay of pions and kaons up to energies of the order of 1 TeV. A value of 0.3&#177;0.2 is estimated for the K/&#960; ratio at production, for muon energies around 500 GeV. A decoherence distribution has been obtained for parallel muon events up to distances of the order of 10 m. From this we conclude that the average Pt of the parents of muons of energy ~250 GeV is of the order of 0.3 GeV/c. From an analysis of rock showers, we obtain the cross section for inelastic interaction of muons of mean energy 100 GeV as (3.8&#177;1.5)&#215;10-30 cm2/nucleon