Biography:

In the past R.K. Manchanda has collaborated on articles with P.C. Agrawal and J.A.R. D’Silva. One of their most recent publications is Ultra-high-pressure proportional counter: Part I: Argon☆. Which was published in journal Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.

More information about R.K. Manchanda research including statistics on their citations can be found on their Copernicus Academic profile page.

R.K. Manchanda's Articles: (13)

Ultra-high-pressure proportional counter: Part I: Argon☆

AbstractLow-pressure argon/xenon-filled proportional counters have been used extensively for the detection of photons and charged particles in the fields of nuclear physics and X-ray astronomy. In general, gas counters have better energy resolution, lower background, simplicity of structure and lower cost compared to semiconductor and scintillation detectors but suffer from low detection efficiency at higher photon energies. To extend the use of gas detectors into the low-energy gamma-ray region, and examine their physical limitations, we have been pursuing a programme to develop and fabricate ultra-high-pressure argon/xenon-filled counting modules with pressures up to 2750 kPa (∼ 400 psi) for the detection of X-ray photons up to 1 MeV. This development is aimed at a new large-area balloon-borne detector system for low-energy gamma-ray astronomy. This paper concerns the detailed description of the gas multiplication behaviour and pulse properties for a detector filled with argon mixtures at high pressures.

Hard X-ray studies with a balloon-borne large area xenon detector telescope

AbstractLarge area multi-layer proportional chambers filled with Xenon have been developed for the study of cosmic X-ray sources in 20 – 100 keV range. The X-ray telescope consists of two such detectors, each having an effective area of 1200 cm2 and equipped with a 5° x 5° FWHM collimator, mounted on a servo-controlled orientation platform for making pointed mode observations. Superior energy resolution of the Xenon detectors, being 10 % FWHM at 22 keV, makes them well suited for detection of cyclotron emission lines in the spectra of X-ray pulsars. The X-ray light curves and energy spectrum of the 4.8 hour binary Cyg X-3, observed in a balloon flight in March 1986 is described.

Transport and recombination of electrons in a high pressure proportional counter using different gas mixtures

AbstractCharge amplification and transport in a cylindrical proportional counter have been studied for a number of gas mixtures at high pressures, as a function of the distance of the primary interaction from the anode. We discuss various known theoretical gas gain formulae, the electron swarm characteristics and transport, and derive information on recombination rates as a function of gas pressure and reduced electric field using spectral analysis.

A high sensitivity payload for balloon-borne hard X-ray astronomy

AbstractA new balloon-borne Large Area Scintillation counter Experiment (LASE) has been built to detect ultrafast variations in the flux of X-ray sources in hard X-ray band upto 200 keV. Presently, the instrument consists of three modules, each made of a 3 mm and a 30 mm NaI(Tl) crystals, arranged in a back-to-back geometry and having an effective area of 400 cm2. In final configuration, the payload will have an area of 2400 cm2. The data is spectrum analyzed in 128 channels between 20 and 200 keV and each event is time-tagged to an accuracy of 25 μs. The estimated sensitivity of the telescope is ∼10−6cm−2s−1 keV−1 for 3 h of source observation. The detector design, background rejection, on-board trigger system, attitude control parameters and the flight performance are described briefly.

High energy X-ray observations of NGC 5506

AbstractWe have a continuing programme of spectral and temporal studies of a variety of galactic and extragalactic sources in the 20–200 keV band using a large area scintillation counter telescope. The observations of NGC 5506, a Seyfert type 2 galaxy, taken on three occasions during the 1998–2000 period suggest that not only source luminosity varies by a factor of ∼10, but also there is a marked change in the spectral index. The data is consistent with a systematic long-term periodic variation. Our analysis of the all sky monitor light curve suggests a 41.12-day period in the source intensity. This paper presents the spectral parameters in the hard X-ray region and proposes that the observed behaviour of the source can be explained on the basis of a binary black hole model for the core activity of the source.

Mechanical properties of ANTRIX balloon film and fabrication of single cap large volume balloons

AbstractThe zero pressure plastic balloons used for high altitude studies are generally made from polyethylene material. Tensile properties of the thin film polymer are the key parameters for material selection due to extremely low temperature of −90 °C encountered by the balloons in the tropopause region during the ascent at equatorial latitudes. The physical and structural properties of the material determine the uniformity of the stress distribution over the entire shell. Load stresses from the suspended load propagate via load tapes heat sealed along with the gore seals as per the balloon design. A balance between this heat seal strength and the film strength is a desirable property of the basic resin in terms of the bubble strength, gauge uniformity, and long-term storage properties. In addition, the design of the top shell of the balloon and its stress distribution play an important role since only a fraction of the balloon is deployed during the filling operation and the ascent. In this paper we describe the mechanical properties of the ‘ANTRIX’ film developed by us and the optimized design of single cap balloons, which have been successfully used in our experiments over the past 5 years.

Characteristics and performance of thin LaBr3(Ce) crystal for hard X-ray astronomy

AbstractWe have developed a new detector using thin lanthanum bromide crystal (32 × 3 mm) for use in X-ray astronomy. The instrument was launched in high altitude balloon flight on two different occasions, December 21, 2007, which reached a ceiling altitude of 4.3 mbs and April 25, 2008 reaching a ceiling altitude 2.8 mbs. The observed background counting rate at the ceiling altitude of 4 mbs was ∼4 × 10−3 ct cm−2 s−1 keV−1 sr−1. This paper describes the details of the experiment, the detector characteristics, and the background behaviour at the ceiling altitude.

Study of seasonal variation of winds in upper stratosphere over Hyderabad

AbstractA predictability of the stratospheric zonal winds above 38 km during the turnaround is an essential parameter for planning of the high-altitude scientific balloon flights. This information is more relevant in the case of Hyderabad balloon facility which is closer to equator and has much more unstable wind reversal patterns which appears to have changed enormously during the last decade probably in correlation with the global warming. With a majority of our flights reaching the altitudes of 38–42 km and the requirement of long float durations, a prior knowledge of wind pattern during the summer and winter turnaround seasons is highly desirable. Furthermore, the flight operation corridor for balloon flights from Hyderabad is limited to 400 km and though in the west direction there are flat lands, in all other three directions, the landscape is dotted by water bodies, reserve forests and hilly terrain, and therefore need of such a data is essential. In order to establish the climatology of the stratospheric winds and study their inter-annual variability over Hyderabad for the turnaround periods, we have made a detailed analysis of the United Kingdom Meteorological office data between 2000 and 2007, to derive average wind parameters (magnitude, direction) at different ceiling altitudes above 38 km. These results can be used only as general trend of stratospheric wind and should not be the limitation of the UKMO Data.

Large area balloon-borne payload for the study of temporal variability in hard X-rays

AbstractThe fundamental parameters of accretion powered X-ray sources are the continuous and homogenous accretion. A breakdown of the homogenous scenario can lead to intensity fluctuations in the entire Fourier space. This paper describes a balloon-borne Large Area Scintillation counter Experiment (LASE) designed to detect microsecond variations in the flux of X-ray sources in hard X-rays upto 200 keV. In final configuration, the payload will have an area of 2400 cm2. Presently, the proto-type instrument consists of two modules, consisting of a 3 mm and a 30 mm NaI(Tl) crystals, arranged in a back-to-back geometry and having an effective area of 400 cm2 each. The data is spectrum analyzed in 127 channels between 20 and 200 keV and each event is time-tagged to an accuracy of 25 microseconds. The detection sensitivity of the telescope is ∼ 2 × 10−6cm−2s−1keV−1 for 3 hr. of source observation. The background rejection, on-board trigger system and other control parameters are described briefly.

Background reduction in a balloon-borne hard X-ray telescope

AbstractWe have been carrying out a series of balloon flight experiments using a large area proportional counter based (xenon filled) hard X-ray telescope and have studied in detail the spectral and temporal characteristics of several cosmic hard X-ray sources. The detector system uses multi-cell multi-layer configuration and for background reduction passive shielding, active anti-coincidence on three sides of the detector and mutual anti-coincidence for the active cells are employed. Further, K-gating technique is used to improve the energy resolution and detection efficiency. We present the effectiveness of the various background rejection techniques using a Monte-Carlo simulation and critically evaluate the possible improvements in the background rejection.

Spatial heterogeneities in aerosol size distribution over Bay of Bengal during Winter-ICARB Experiment

AbstractThis work examines the aerosol physical properties and size distribution measured in the Marine Atmospheric Boundary Layer (MABL) over entire Bay of Bengal (BoB) and Northern Indian Ocean (NIO) during the Winter Integrated Campaign on Aerosols, Gases and Radiation Budget (W-ICARB). The measurements were taken using the GRIMM optical particle counter from 27th December 2008 to 30th January 2009. The results show large spatial heterogeneities regarding both the total aerosol number concentrations (NT) and the size distributions over BoB, which in turn indicates the variations in the source strength or advection from different regions. The aerosol number size distribution seems to be bi-modal in the 72% of the cases and can also be parameterized by uni-modal or by a combination of power-law and uni-modal distributions for the rest of the cases. The mode radius for accumulation and coarse-mode particles ranges from ∼0.1–0.2 μm and ∼0.6–0.8 μm, respectively. In the northern BoB and along the Indian coast, the aerosols are mainly of sub-micron size with effective radius (Reff) ranging between 0.25 and 0.3 μm highlighting the strong anthropogenic influence, while in the open oceanic areas they are much higher (0.4–0.6 μm). It was also found that the sea-surface wind plays a considerable role in the super-micron number concentration, Reff and mode radius for coarse-mode aerosols. Using the relation between NT and columnar AOD from Terra and Aqua-MODIS we found that the majority of the aerosols are within the lower MABL, while in some areas vertical heterogeneities also exist.

Transport of tropospheric and stratospheric ozone over India: Balloon-borne observations and modeling analysis

Highlights•Balloon-borne in-situ measurement of tropospheric and stratospheric O3 over India.•Role of central African and Southeast Asian air masses in tropospheric enhancements of O3 over India.•Inter-comparison of vertical O3 profiles with MACC-II and CCM2 simulation.•Large contribution of the FT-O3 to the tropospheric column O3 (TCO) over both sites of HYD and TVM.

ClinicalHomeopathy in the treatment of tubercular lymphadenitis (TBLN) – An Indian experience

Tuberculosis (TB) has been known since antiquity. In spite of effective antibiotic treatment, it is still a major worldwide public health problem. Endogenous factors are important in the development of active disease. Homeopathic medicines have the potential for immune-modulation and hence to influence endogenous factors in disease.In India, patients with tubercular lymphadenitis (TBLN) often consult homeopaths but such cases are seldom documented. The objective of the present study is to document such experience. A retrospective exploratory study of 25 positively diagnosed cases of TBLN has lead to the development of a homeopathic regime consisting of a patient specific constitutional medicine, one disease specific biotherapy (Tuberculinum) and Silicea 6x as supportive medicine. Homeopathy can be used as a complement to conventional anti tubercular treatment (ATT) with beneficial results.Further validation in controlled trials with immunological markers is required.

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