Archives of NA31 Experiment, Liquid Argon Calorimeter

Identity Statement [Top]

Reference code(s)

CERN-ARCH-NA31-001 to CERN-ARCH-NA31-010


Archives of NA31 Experiment, Liquid Argon Calorimeter



Level of description


Extent of the unit of description

10 files, 0.6 linear metres

Context [Top]

Name of creator

NA31 Experiment Collaboration

Administrative history

Experiment NA31 (North Area of SPS) is a CERN - Edinburgh - Orsay - Mainz - Pisa - Siegen Collaboration which began in 1979.

The aim of this experiment was an accurate determination of the ratio of neutral to charged two pion decays of mesons: In the superweak model of CP violation this ratio is equal to one exactly. Sizeable deviations from unity were predicted in popular models of the weak and electromagnetic interaction among six quarks.

The NA31 cryostat is composed of an inner (liquid argon) vessel, an outer (vacuum) vessel, two large front and back flanges and a cover plate. The inner stainless-steel vessel is sealed to the outer one by means of an O-ring. The warm cover plate, which supports the calorimeter, seals the liquid-argon vessel without any vacuum insulation. The necessary feedthroughs for signal, HV and liquid transfer pass through the cover plate. The outward pressures on the liquid-argon vessel are transferred to the beam windows by means of truncated G10 cones.

The dimensions of the internal liquid-argon vessel are: 0.75 m along the beam, 2.80 m in the transverse direction and 3.7 m in height. The total material in front of the active part of the calorimeter amounts to 0.90 radiation lengths. Finally, the thermal loss of the cryostat is about 1500 W, divided into: 50% due to solid conduction, 25% due to radiation, and 25% to convection and transfer losses.

The neutral kaon beam covers the 50-150 GeV energy range. More than 10 useful decays, and correspondingly more for the over decay modes, have already been collected.

The NA31 experiment finished in 1991, but continued renamed NA48 with more intense kaon beams and a new detector free of the errors intrinsic to the original experiment.

* Source: Greybook (list of CERN experiments)

Immediate source of acquisition or transfer

Gerhard Kesseler, Main Engineer of NA31 Experiment.
Heinrich Wahl, Former Spokesman of NA31 Experiment.

Content & Structure [Top]

Scope and content

This collection covers the period 1979-1991. It contains documents about financing (internal buying, applications, technical enquiries) and exploitation (calculations, design studies, check papers, technical specifications) of NA31. It also contains memoranda, correspondence, logbooks, drawings, security instructions and minutes of weekly meetings.

Appraisal, destruction and scheduling information

Nothing was destroyed.


No further accruals are expected.

System of arrangement

CERN-ARCH-NA31-001 Orders
CERN-ARCH-NA31-002 Read out - conversation plates
CERN-ARCH-NA31-003 Instrumentation
CERN-ARCH-NA31-004 Cryostat
CERN-ARCH-NA31-005 Components
CERN-ARCH-NA31-006 Design considerations
CERN-ARCH-NA31-007 Cryogenic equipment
CERN-ARCH-NA31-008 Transition radiation detector construction
CERN-ARCH-NA31-009 Prototype (Logbook)
CERN-ARCH-NA31-010 Construction (Logbook)

Conditions of access and use [Top]

Conditions governing access

See file level description and the CERN operational circular No 3: rules applicable to archival material and archiving at CERN. In general, records on any subject that are over 30 years old, and all records of a purely scientific nature, may be consulted.

Conditions governing reproduction

Copyright is retained by CERN, no reproduction without permission.

Language / scripts of material

Most of the material is written in English, French or German.

Finding aids

Listed to file level in the CERN Archives Database.

Description control [Top]

Archivist's note

Description prepared by Marie Coosemans

Date(s) of description

Geneva, the 28th July 2004, Revised 2007.