SPHERE PEG GAY FAIRBURY JR SR HIGH SCHOOL

PROJECT SPHERE  Cherenkov light: radiation which is emitted whenever charged particles pass through matter with a velocity v exceeding the velocity of light in the medium. The intensity is proportional to the energy of a primary cosmic ray particle. An experiment to measure primary cosmic ray spectrum by detecting Cherenkov light reflected from the surface of snow covered ground. Also to detect atmospheric fluorescence. Equipment is ground based, and balloon-borne

Where is SPHERE? At the Nuclear Physics Institute of Moscow State University Group Leader for the SPHERE Project is Dr. R.A. Antonov This project is based on ideas of Professor A.E. Chudakov

Reasons for SPHERE 1.Ties together data of an orbital experiment with a ground based experiment 2.Two types of detection for cosmic rays: atmospheric fluorescence and Cherenkov light from snow. 3.Optimized analysis of data by an on-board computer. 4.Real light background value for the boundary of the atmosphere 5.Protection of detectors from night and day light changes in conditions. 6.Cheaper than installing equipment on spacecraft.

Equipment for SPHERE This equipment is used to make measurements in an energy range of to eV The electronics measure  The integral of light pulses  Duration between pulses  Arrival direction of rays

19 Photo- multiplier tubes are located at the focal point of the spherical mirror, in a honeycomb pattern. Detector Array Filters are used to decrease light interference from the starlight background.

How It Works EAS – Extended Air Shower At an altitude of 40 km detectors can cover an area of 1000 km 2

Two data collecting missions Thain-Shan mountains, surface mounted experiment balloon-borne experiment at an altitude of 0.9 km from earths surface the detector SPHERE was significantly improved. Proposed mission to carry out a high altitude balloon-borne experiment.

Ground Based Test  Winter 1993 – B.Alma-Ata Lake  160 meter ledge, covers the entire lake surface.

DATA From Ground Based Test The graph is of a differential energy spectrum. Left arrow: Knee Right arrow: Ankle

White dots: uncovered PMT’s – 4871 events in 1510 minutes Black dots: covered PMT’s – 1613 events in 956 minutes PMT’s were covered to collect data on direct cosmic ray activity, and incidental particles. The Cherenkov reading is obtained from the difference between the two scales on the graph

Pictures of Balloon-borne Experiment

More Pictures

Data from balloon-borne experiment  Method of detection was appropriate.  Monte-Carlo simulations used and recorded  Data from the experiment was not included. TABLE 1. Estimation of EAS with E>Eo number to be detected by SPHERE detector. fastened balloon fastened balloon at the South Pole 4flights of balloon around the Source Pole E o, eV I(>E o ), (m 2 hour sr) -1 H, km S, m 2 Ethr, eV t, hour (20 days)

Future of SPHERE Future experimentation was designed which included high altitude (1 – 3 km) data gathering, but no information was available as to whether this experiment has taken place or will yet be implemented, perhaps, funding has been an issue or equipment breakage or loss, all pure speculation on my part.

Conclusion Ground based, low altitude and high altitude balloon-borne experiments Cherenkov light and atmosphere fluorescence detection. The experiment did show this method of detection appropriate for cosmic ray measurements. Measuring a wide range of energies over a large sensitive area using the balloon-borne detector is possible.