Speaker
Mr
Satyanarayana Bheesette
(TIFR)
Description
India-based Neutrino Observatory (INO) collaboration is proposing a large magnetized
iron tracking calorimeter of total weight 50 kton, using atmospheric neutrinos as
source. The proposed detector will have a modular structure of lateral size 48 m16 m
and will consist of a stack of 140 layers of 6cm thick iron plates interleaved with
Resistive Plate Chamber (RPC) detector layers. A total of about 27, 000 RPCs of
dimension 2mX2m will be needed for his experiment. A dedicated effort for development
of RPC detectors, leading to their large scale production is in progress.
A large number of single gap glass RPCs of area 3030 cm2 as well as a few of area
12090 cm2 were developed, using glass procured from local market. The V-I
characteristics of these detectors were studied. The noise rate was found to be a
reliable way of monitoring the stability of the RPC. Plateau efficiencies of over 90%
for various gas mixtures have been obtained for minimum ionizing particles.
Measurements of the charge linearity and time response of the RPC as a function of
applied high voltage have been made. The typical time resolution of the RPCs when
operated in the operating voltage plateau is about 1.2 nSec. We have also built a
couple of chambers using glass imported from Japan. These chambers are now in
undergoing a long term stability tests and are in continuous operation for about six
months.
We have setup a second RPC test station during the past few months. This is equipped
with a sophisticated gas mixing, telescope and data acquisition systems. The gas unit
is capable of mixing four input gases in the desired proportion and flow through 16
channels. We are currently operating a stack of 10 RPCs of one square foot in area in
the streamer mode in this station. Triggered by a scintillation paddle based
telescope, we are able to track cosmic ray muons and record their timing, using this
stack.
We will a give summary of earlier results and discuss current status and future
directions of this detector R & D programme.
