IONS (ANURADHA): Ionization states of low energy cosmic rays

IONS (ANURADHA), the experimental payload designed specifically to determine the ionization states, flux, composition, energy spectra and arrival directions of low energy (10 to 100 MeV/amu) anomalous cosmic ray ions of helium to iron in near-Earth space, had a highly successful flight and operation Spacelab-3 mission. The experiment combines the accuracy of a highly sensitive CR-39 nuclear track detector with active components included in the payload to achieve the experimental objectives. Post-flight analysis of detector calibration pieces placed within the payload indicated no measurable changes in detector response due to its exposure in spacelab environment. Nuclear tracks produced by alpha-particles, oxygen group and Fe ions in low energy anomalous cosmic rays were identified. It is calculated that the main detector has recorded high quality events of about 10,000 alpha-particles and similar number of oxygen group and heavier ions of low energy cosmic rays

A detector for determining the direction and energy of fast neutrons in cosmic radiation

A method based on the reaction <SUP>10</SUP>B+n&#8594;<SUP>4</SUP>He+<SUP>4</SUP>He+<SUP>3</SUP>H++0.3 MeV for determining both the direction and the energy of fast neutrons of cosmic rays in the energy interval about 20-100 MeV is described. A test experiment was made using a small nuclear emulsion stack loaded with 95% enriched <SUP>10</SUP>B-isotope and flown in a balloon flight from Hyderabad, India in March 1968. A kinematical method is described for rapid selection of <SUP>10</SUP>B events and the background effect is estimated. The momenta, energies and arrival directions of a sample of fast neutrons are determined

Cutting thin sheets of allyl diglycol carbonate (CR-39) with a CW CO<SUB>2</SUB> laser: instrumentation and parametric investigation

Recent studies have shown that Allyl Diglycol Carbonate, commercially known as CR-39 (the most sensitive among etch track detectors) can detect relativistic oxygen and other heavier nuclei. We are using large sheets of special grade CR-39 (DOP) in our experiment in Space Shuttle Spacelab-3. As CR-39 is a highly brittle substance, special care is required to cut CR-39 sheets, especially in case of large sheets and circular cuts. A study of cutting of CR-39 sheets using laser light is described in this paper. It has been found that this method is sufficiently fast to handle large number of sheets and also equally safe for big sheets. A maximum speed up to 200 cm/min with a 5&#215; 10<SUP>4</SUP> W/cm<SUP>2</SUP> laser is obtained during the present study. This study also shows that laser cutting does not affect the track properties of CR-39

ADC (CR-39) detector module for space shuttle spacelab-3 cosmic ray experiment

In recent years, some experimental studies have reported the presence of a new component in low energy heavy cosmic rays in near earth space. The Indian cosmic ray experiment aboard Space Shuttle Spacelab-3 is designed to study the ionization states of this new component in addition to its abundance and energy spectra. This experiment will be flown in space in Spacelab-3 in 1984. Our detector system consists mainly of CR-39 (DOP) sheets along with some Lexan Polycarbonate sheets. In this paper, we describe the detector module for this experiment along with its functioning

Indian cosmic ray experiment ions (Anuradha) in space shuttle spacelab-3 using CR-39 detectors

An Indian experiment in spacelab-3 has been designed to perform the measurements of ionization states, flux and energy spectrum of elements of Z = 2-26 in the anomalous component of cosmic radiation in the energy region 5-100 MeV/amu. In this experiment, we are using thin CR-39 (DOP) sheets (thickness 250μm) specially prepared by Pershore Moulding Ltd., England, using 32 hrs. curing cycle and 1% dioctyl phythalate. Our study of track response does not show any significant depth dependence or surface to surface variation for this detector. The detector calibration to different accelerated heavy ion beams is presented in separate paper in this conference. The alignment of different sheets in detector module is done using 50 MeV a-beam from VECC, Calcutta, India. The detector module consists of two stacks. The bottom stack is rotated in discrete steps of 40 arc sec once in every 10 sec below top stack which is fixed with main instrument body. This will give time information for each event. The threshold rigidity of the particle will be calculated from arrival time information, spacelab data and trajectory calculations. The lower bound ionization state of a particle can be determined from magnetic threshold rigidity and its total energy. The energy is determined by measuring the total ranges of arriving particles in bottom stack. The 45 kg instrument was successfully flown in NASA's space shuttle spacelab-3 mission during April 29 to May 6, 1985 at an altitude of 352 km and an inclination of 57° latitude

Ionization states of cosmic rays: Anuradha (IONS) experiment in Spacelab-3

The measurements of the ionization states, composition, energy spectra and spatial distribution of heavy ions of helium to iron of energies 10-100 MeV/amu in the anomalous cosmic rays are of major importance in understanding their origin which is unknown at present.Anuradha (IONS) cosmic ray experiment in Spacelab-3 was designed to determine the above properties in near earth space and this had a highly successful flight and operations aboard the shuttle Challenger at an orbital altitude of 352 km during 29 April to 6 May 1985. The instrument employs solid state nuclear track detectors (CR-39) of high sensitivity and large collecting area of about 800 cm2 and determines the arrival time information of particles with active elements. Experimental methods, flight operations and preliminary results are briefly described. Initial results indicate that relatively high fluxes of low energy cosmic ray &#945;-particles, oxygen group and heavier ions were obtained. The flight period corresponded to that of quiet Sun and the level of solar activity was close to solar minimum. It is estimated that about 10,000 events of low energy cosmic ray alpha particles with time annotation are recorded in the detector together with similar number of events of oxygen and heavier ions of low energy cosmic rays