Cosmic Rays in Peru

1. Cosmic Rays in Peru • The Cosmic Rays in Peru • By • José Ishitsuka and Hugo Trigoso • pepe@geo.igp.gob.pe trigoso@geo.igp.gob.pe • Ancon Observatory • Instituto Geofísico del Perú • IGP

2. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru • History about the observations of Cosmic Rays. “From a consideration of the immense volume of newly discovered facts in the field of physics, especially atomic physics, in recent years it might well appear to the layman that the main problems were already solved and that only more detailed work was necessary. This is far from the truth, as will be shown by one of the biggest and most important newly opened fields of research, with which I am closely associated, that of cosmic rays. When, in 1912, I was able to demonstrate by means of a series of balloon ascents, that the ionization in a hermetically sealed vessel was reduced with increasing height from the earth (reduction in the effect of radioactive substances in the earth), but that it noticeably increased from 1,000 m onwards, and at 5 km height reached several times the observed value at earth level, I concluded that this ionization might be attributed to the penetration of the earth's atmosphere from outer space by hitherto unknown radiation of exceptionally high penetrating capacity, which was still able to ionize the air at the earth's surface noticeably...” Dr. Victor F. Hess' Nobel Lecture, in 1936

3. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru By middle of 1935 five precision recording cosmic-ray meters C model, based on a design developed by Professor R.D. Bennett at MIT and Professor A. H. Compton at Chicago University, were constructed. And deployed over the world In order to have simultaneous and continuous records of Cosmic-rays flux. Increments of intensity of CosmicRays, Feb/28 and March/7 1942

4. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru By middle of 1935 five precision recording cosmic-ray meters C model, based on a design developed by Professor R.D. Bennett at MIT and Professor A. H. Compton at Chicago University, were constructed. And deployed over the world In order to have simultaneous and continuous records of Cosmic-rays flux. Increments of intensity of CosmicRays, Feb/28 and March/7 1942

5. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Aerial view of Huancayo Observatory looking from northwest Aerial view of Huancayo Observatory, looking from northwest

6. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Aerial view of Huancayo Observatory looking from southeast

7. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Cosmic–ray building at Huancayo Observatory (1935)‏

8. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru • Cosmic-ray meter (C2) at Huancayo Observatory The Instrument consist of a spherical steel ionization chamber , the volume is about 19.3 liters, filled with a pure argon at 50 atmospheres. Because at this pressure the ionization is 67 times more than in the normal pressure. A balancing current is supplied by ionization produced in a small auxiliary chamber, inside sphere by β rays from metallic uranium

9. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru • Cosmic-ray meter at Huancayo Observatory (2008).

10. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Cross-section view of apparatus, showing details of the central electrode, β chamber and micrometer for adjusting the position of uranium By turning the micrometer rod to which the uranium is attached permits varying the rate of entry of β-rays into the balance chamber as a consequence of changes of amount of shielding. The balance current can thus be made about equal, and in opposite in sign through choice of sweep field, to the average ionization current produced in the main chamber by cosmic rays.

11. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Electrometer box, optical system, Barometer and Recording Camera This permits ample sensitivity for recording , on a photographic trace 60mm wide changes in ionization due to cosmic rays. This method of balancing also compensates for changes in ionization which might result from changes in pressure or temperature, because the fact that ionization current due to β-rays in the balance chamber is affected in the same way as that due to due to cosmic rays in the main chamber

12. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Cosmic-ray records Huancayo Observatory, in 1936 Records of cosmic-rays from Huancayo Observatory, vertical lines are hour- marks. The upward slope of the electrometer trace indicates that the balance current exceeds the cosmic-ray ionization current. These records corresponds to January 1936 during the commencement of a magnetic storm.

13. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Calibration Curves, giving the residual ionization in a mine 110 meters below the surface . In this figure, ia is the current in the main ionization chamber, due chiefly to cosmic rays. ib is the current in the balance chamber due chiefly Beta rays

14. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Barometric coefficient for Cosmic-ray Intensity at Huancayo Observatory from correlation between average departures in Cosmic-ray intensity and in barometric pressure from means of selected days. Days were selected from weekly intervals with great changes in pressure. The regression coefficient is 0.99

15. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru • CONTRIBUTIONS OF HUANCAYO OBSERVATORY • The quasi-persistent 27-day variation of intensity; • The diurnal variation of intensity; • The absence of a detectable sidereal diurnal variation of intensity; • The sporadic emission of very energetic (up to several GeV) charged particles by solar flares; • Worldwide impulsive decreases (Forbush decreases) of intensity followed by gradual recovery; • The 11-year cyclic variation of intensity and its anticorrelation with the solar activity cycle as measured by sunspot numbers; and • The 22-year cycle in the amplitude of the diurnal variation.

16. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Three unusual increases in cosmic-ray Intensity during solar flares and radio fadeout

17. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Increment of cosmic Rays, Nov/19/1949 This unusual increment of Cosmic ray have been produced one hour later the observed solar flare

18. Cosmic Rays in Peru Daily means of Cosmic-ray intensity and horizontal magnetic intensity, showing effect of magnetic storm of April 25-30, on cosmic-ray intensity.

19. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Harmonic Dials of Time Periodic intensity of cosmic rays This shows the cyclic nature in the 27 days variation

20. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru The effects of magnetic storm over the daily mean values of cosmic radiation. in Boston, Chentelham and Huancayo.

21. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Average difference for cosmic-ray Intensity (ΔC) and for horizontal magnetic field (ΔH) for five disturbed days less that for five quiet days in each month, April, 1937 – December 1946at Huancayo Observatory. These differences are preponderantly negative and correlated between the two stations, showing that the cosmic-ray intensity definitely tends to be less on magnetically disturbed than on magnetically quiet days. These differences are all negative and vary (algebraically) roughly with the sunspot cycle.

22. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru Annual means: Sunspot numbers and variability cosmic-ray Intensity at Huancayo Observatory. Cosmic-ray intensity at Huancayo in the period 1937-1955 is least in the years on minimum solar activity, and increases near sunspot maxima.

23. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru

24. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS Cosmic Rays in Peru

25. THIRD SCHOOL ON COSMIC RAYS AND ASTROPHYSICS CosmicRays in Peru THANK YOU VERY MUCH