The NA48 Liquid Krypton Calorimeter Project
Cagliari-Cambridge-CERN-Dubna-Edinburgh-Ferrara-Firenze-Mainz
Orsay-Perugia-Pisa-Saclay-Siegen-Torino-Vienna-Warsaw Collaboration
Presented by A. Ceccucci
CERN, PPE Division
1211 Genève 23
INST96, Novosibirsk
5 March 1996
Conclusions
The CERN-NA48 Experiment
The NA48 collaboration is preparing a new experiment
to measure 
with an accuracy of 
.
The principle of the experiment is to collect the four relevant
decay modes concurrently, in the same detector
using almost
collinear K 
and K 
beams,
distinguished by
tagging
the proton which produces the K particle.
The charged decays will be
reconstructed by a magnetic spectrometer.
To reconstruct the neutral
decays, a good electro-magnetic calorimeter is needed.
Specs for the NA48 calorimeter
Main background : 
with missing
photons.
In order to reconstruct the
decay position
to 
50 cm, and
to 1 MeV we need:
Homogeneous calorimeter
1 mm 
Good granularity
constant term Accurate geometry and precise
calibration
Tower structure and fast read-out
Moreover in order to tag 
decays with the proton beam upstream
the target a time resolution < 0.5 ns is also needed.
The fiducial region of the calorimeter is contained between two circles of
300 and 2400 mm placed 100 m from the
begin of the Kaon decay region.
Choice for the NA48 calorimeter
The NA48 choice has been a quasi-homogeneous liquid krypton ionization chamber with tower structure read-out.
1250 mm of active
LKr are used ( 25 X 
).
Kr natural radioactivity doesn't affect
the energy resolution
since it is negligible with respect to the electronics noise.
120 K implies the use of cryogenics vessels.
On one side this
causes the presence of material in front of the active Kr, but on the other
end allows a good control of the bath temperature
(to 0.1 K).
One electrode