CosmicRay Research in India印度宇宙线的研究

1、cosmic ray research in indiaa historical perspectivesuresh c. tonwartata institute of fundamental research, mumbai joined as research associate (august 1962); retired as senior professor (may 2006)visiting senior scientist, department of physics, university of maryland, college park, md 20742, usare

2、view meeting grapes experiment cosmic ray laboratory (tifr), ooty; january 4, 2008cosmic ray particle physics (1940-80)cosmic ray astrophysics (1980- . ) ground-based observations in 1920s and 30s by d.m. bose, vibha choudhury et al in kolkata. balloon-borne observations by homi bhabha at i.i.sc., b

3、angalore in early 1940s. tata institute of fundamental research set up in june 1945 by the dorabji tata trust and the government of bombay for research in nuclear sciences, including cosmic rays, and mathematics.cosmic ray research centres in india bombay (tifr and barc) ahmedabad (prl) bangalore (i

4、isc, iia, rri) universities aligarh, delhi, durgapur, gauhati, jadavpur, north bengal, panjab, .cosmic ray research particle physics era cosmic ray studies at tifr - inspired and motivated by homi bhabha, observations on cosmic rays was a major research program in tifr from its very beginning. a clo

5、ud chamber and trays of geiger-muller counters were in operation at tifr as early as 1948 to observe muons traversing different materials (b.v. sreekantan). primary cosmic rays : studies on primary cosmic rays and particle interactions with nuclear emulsion stacks and particle detectors flown on bal

6、loon-borne platforms, launched from the national balloon facility, hyderabad, during 1950s and 60s. secondary cosmic rays: measurements on the flux and angular distribution of muons at various depths underground in kgf during the early 1950s using a 900 cm2 area gm counter hodoscope (s. naranan and

7、b.v. sreekantan).observations on muon interactions in kgf using a cloud chamber (s.naranan and b.v. sreekantan).direct studies on interactions of hadrons with carbon and brass targets during 1960-63 at ooty using multiplate cloud chamber (a. subramanian, s.lal, et al.)studies on hadrons in extensive

8、 air showers (eas) during 1963-73 at ooty (b.k. chatterjee, s.c. tonwar, r.h. vatcha et al).studies on high energy muons in eas during 1963-83 at kgf (r. srikanta rao, b.s. acharya, m.v. s. rao, k. sivaprasad et al). studies on muons and neutrinos (and proton decay) during 1960-90 at kgf (m.g.k. men

9、on, s. miyake, a.w. wolfendale, p.v. ramanamurthy, v.s. narasimham, b.v. sreekantan et al). interactions of muons - in 1954, a.b. sahiar, an expert on cloud chambers who received his training in blacketts laboratory in u.k., started a program for the study of muon interactions in an abandoned railwa

10、y tunnel near khandala in western ghats using a self-contained mobile cloud chamber laboratory which showed complete consistency of the observations with the expectations from quantum electrodynamics. these observations motivated homi bhabha to initiate a search for a new site for a high-altitude la

11、boratory for studies on interactions of mesons and nucleons using cloud chambers. cosmic ray laboratory at ooty - after careful evaluation of various possible sites spread all over the country, including ooty and kodaikanal in the south and gulmarg in the north, the cosmic ray laboratory of tifr was

12、 set up at ooty in december 1954, thanks to the generous offer by the then governor of madras, to prof. bhabha to use some of the building within the premises of the raj bhavan for the first experiments. the first observations on the interactions of muons and hadrons were made in late 1950s here at

13、ooty using two multiplate cloud chambers placed one above the other. ooty (11o 23 n, 158o 55 e, 2200 m) is also known as ootacamund or udhagamandalam (s. lal, yash pal and a.b.sahiar). direct studies on interactions of hadrons with carbon and brass targets during 1960-63 at ooty using a small multip

14、late cloud chamber (a. subramanian, s.lal, et al). studies on hadrons in extensive air showers (eas) during 1963-83 at ooty using the scintillator-iron plates sandwich hadron calorimeter and the large multiplate cloud chamber (b.k. chatterjee, s.c. tonwar, r.h. vatcha, b.v. sreekantan et al).particl

15、e physics with cosmic rays results from observations on hadrons in air showers at ooty measurements were made on the arrival delay spectrum for hadrons, relative to the shower front, by timing the signals from the calorimeter. detailed comparison of observations on delayed hadrons with monte carlo s

16、imulations led to the conclusion that the baryon production cross-section was increasing with energy (s.c. tonwar et al).air cherenkov counter for particle identification (pion, proton, neutron)multiplate cloud chamber with carbon and brass plates for interaction display25-layer iron plate-scintilla

17、tor calorimeterdirect studies on particle interactions at ooty (1960-63)arrival delay spectrum for hadrons in eas increase in baryon production cross-section at 1014-15 evparticle physics with cosmic rays results from observations on hadrons in air showers at ootyobservations on high energy hadrons

18、with the large multiplate cloud chamber provided unique and significant results on two aspects of high energy particle interactions.energy spectrum of hadrons was found to be very steep, over the 100-1000 gev range, requiring a significant increase in proton-air and pion-air interaction cross-sectio

19、n with increasing energy.presence of a large number of neutral particles (mostly neutrons) among the high energy hadrons required an increase in the baryon production cross-section with increasing energy, a result obtained independently by the ooty group from studies on arrival time distribution of

20、lower energy, 10-20 gev, hadrons (r.h. vatcha et al). ooty cloud chamber: single high energy hadron interacting inside the chamberooty cloud chamber: single high energy hadron interacting in the shielding above the chamber or in airooty cloud chamber: large number of hadrons incident on the chamber

21、core of an eas high energy muons - observations in kgf mines in early 1960s to obtain the depth-intensity curve up to the largest depths possible. at the lowest depth (2760 m), no count was recorded in 60 days setting an upper limit of 10-11 muons cm-2 s-1 sr-1. these measurements provided informati

22、on on the interactions of very high energy muons, particularly the nuclear interactions and set a new lower limit on the mass of the intermediate vector boson mediating the weak interactions (m.g.k. menon, s. miyake, v.s. narasimham and p.v. ramanamurthy). interaction of atmospheric neutrinos - the

23、first direct observation of an interaction of an atmospheric neutrino within a detector was made in kgf in april 1964 by the dot collaboration. this was followed by a similar observation a week later by the uci-led collaboration (fred reines et al) in a mine in south africa. search for proton decay

24、- the capability of the experiments carried out deep underground ( 2.3 km) in kgf mines for efficiently filtering all cosmic ray particles except neutrinos led the ocu-tifr collaboration to install a 140-ton detector in 1980 to search for the decay of protons with a lifetime 1030 years as predicted

25、by the grand unification theory of salam and glashow. unfortunately, the plans of the collaboration to upgrade this detector to enhance its sensitivity beyond 1031 years were aborted by the decision of the goi to close the kgf mines in early 1990s due to economic reasons. cosmic ray research high en

26、ergy astrophysics era (1977 present)primary cosmic ray spectrum (107 to 1020 ev)the knee and the ankle in the cosmic ray energy spectrumcosmic ray sources: acceleration & propagation study of the elemental and isotopic composition of cosmic rays at gev-tev energies using balloon or satellite-bor

27、ne detectors (e 1 gev) was installed during 1989-92 to improve the sensitivity of the experiment for detecting gamma-ray initiated showers from cosmic sources. the grapes-2 array has been taking data continuously since 1992 to search for bursting sources of uhe gamma rays.100-detector grapes-2 array

28、 at ooty (1992)muon multiplicity distribution expected for various primary nuclei (same eo) grapes-2 at ooty muon multiplicity distribution expected for various primary nuclei (shower trigger) grapes-2 (ooty)a comparison of the observed muon multiplicity distribution with simulations grapes-2 at oot

29、ygrapes-3 experimet at ooty (2000 present) phase 1primary objectives:observations on muon multiplicity distributions for small showers using the 16-module 560 m2 area muon detector (e 1 gev) and the 217-detector air shower compact array.determination of the energy spectrum of major nuclear groups (protons, he, cno, si and fe) at low energies (30-300 tev) overlapping with measurements by the balloon and satellite-borne detectors validation of a proper high energy particle interaction model.search for uhe gamma ray sources in steady as well as sporadic emission modes usin