Front Ranking Cosmic Ray Experiments carried out in the late

40’s and 50’s at TIFR with Home-Made Detectors and Electronics

Panel Discussion, TIFR, Mumbai15 January 2010

1. Mu-meson Life Time and decay spectrum (1948-51) : BVS

Harold Tycho working under Prof. Rossi – publishes his results in Phys. Rev.

• Microsecond Electronics• Triggered Oscilloscope• Pulsed Circuits • Iron Magnet

All with military disposal valves brought from Chor Bazar

• GM counters with double-distilled alcohol as quenchers.

(Nucleonic Elmore and Sands)

Experimental arrangement II: Positive mesons focussed into the paraffin absorber

in which they decay, by the magnetic lens M.

Typical oscilloscopic records of the -meson decay events registered.

2. KGF Experiments 1st phase 1951 onwards.

First Elementary Particle Conference in Bombay, Dec. 1950

• KGF 2nd phase

Ratio of k’s to Pi’s

(1951-53)

1954 : Khandala Cloud Chamber in Railway Tunnel (200 ft)

18” cloud chamber built in TIFR workshop

• Intensity-Depth upto 1000 ft with Hodoscoped Telescope (BVS + SN) Bhabha suggets to verify whether all underground particles are muons

Angular Distribution of muons at various Depths.Cloud Chamber at depth of 100 ft in search of APP’s

(BVS+SN+PVR)

ABS+BVS+SN+PVR

Search of APP’s continued.

3. 1954-55 MIT – Echo Lake Cambridge (Mass.)

HP 327 Oscilloscope Nanosecond timing made possible. Bhabha orders

even before my return.

Book: Millimicrosecond Pulse Techniques

S-particles (k2 , k3)

Development of Chronotron – Measurement of Nanosecond Timing for Air Shower Experiments

Scintillation Counter for EAS – Bombay: TIFR 3rd Floor; Ooty: Raj Bhavan

Rani and Maharani Cloud Chambers at Ooty- S-particle Searches

Development of Spark Counters

Cores of Extensive Air Showers

Development of Total Absorption Spectrometer (TASS)

Triple setup; Cloud Chamber + Air Cerenkov Counter + TASS

Large Cloud Chamber – Largest in the World (Miyake)

Photograph of a completely assembled spark counter: (a) aluminium angles to keep the plastic frame straight; (b) plastic frame 60 cm x 30 cm; (c) stainless steel plate 50 cm x 30 cm x 3 mm; (d) brass welding

rods 58 cm long, 3 mm diameter.

Experimental arrangement to test the feasibility of employing nuclear emulsions in conjunction with double spark counter array for the study of high energy jets.

The coincidence G1SG2 selects nuclear interactions produced mostly in the water tank. The lead plates above the spark counter are meant for the rapid development of the cascades. The direction and co-ordinates of the jets are

given by the position of the sparks in the two spark counters.

Photograph of a typical double spark event. The sparks have occurred (shown AA) in the right extreme compartment in both the counters. The bright strips seen in the photograph

correspond to the portions of brass rods below the ribs of the plastic frame illuminated for a short time, immetiately after photographing the sparks but before advancing the film. This

serves as a convenient reference frame for locating sparks.

Cloud chamber photograph of a high energy penetrating shower proceed in the lead block above the chamber and developing further in the lead plates side. A spark was seen in the spark counter in the region through which the axis of the shower passed the spark counter.

An enlarged view of the section of two adjacent layers of the spectrometer showing the details of design of the liquid

scintillation tank.

A cross sectional view of the total absorption scintillation spectrometer (TASS) and the shower detector.

Schematic diagram of the chronotron system for measurement of arrival time of the hadrons signal from TASS relative to the signal from the shower detector CHO.

A block diagram of the circuitry associated with the

spectrometer.

Comparison of the observed time spectra for hadrons of (10 20 GeV energy with spectra calculated using different models of high-energy hadron collisions. The statistical errors as well as the errors in the measured arrival time are shown on each experimental point except the aero-time point which is free of timing errors. Is the average shower size and R is the distance of the hadron from shower axis, = 102, R 20 m.

experimental data--------- calculations.

eN

eN

Triple arrangement of Air Cerenkov Counter, Multiplate Cloud Chamber and Total Absorption Spectrometer at Ooty, for the study of interactions

of pions and protons in 10-100 GeV range.

A cascade which develops from the first plate of the chamber and shows a rapid absorption after the maximum. The method of cascade widths has been used for energy estimation which is 750 GeV.

Several cascades having elongated tube-like structures not completely absorbed even after 20 radiation lengths. The estimated energy of the largest cascade is 2.4 TeV.

Core Regions of Extensive Air Showers

Ooty Team:

BVS + SN + AS + PVR + SL + SDV + TNR + GTM + BKC + MVS + RR + RHV + SCT

+ (Miyake)

Dinshaw + Apte + Khairatkar + Kalagaonkar + Gonsalves + Manchanda + Gopal

KGF Team: BVS+SN+ MVS + PRV + KS + VSN + MGK + KA + British +

Japanese