New Measurements Reported by the Sudbury Neutrino Observatory (Forwarded)

Sudbury Neutrino Observatory
Sudbury, Ontario, Canada

NEWS RELEASE: September 7, 2003, 11:45 am Eastern Daylight Time

New Measurements Reported by the Sudbury Neutrino Observatory

A common table commodity that people sprinkle on their food every day is the
main ingredient in new measurements by scientists at the Sudbury Neutrino
Observatory (SNO). In a presentation Sunday, September 7, 2003, at TAUP 2003, a
major scientific conference in Seattle, Washington, new measurements are
reported that strongly confirm the original SNO results announced in 2001 and
2002 that solved the "Solar Neutrino Problem" and go much further in
establishing the properties of neutrinos that cause them to change from one type
to another in transit to the Earth from the Sun. "We have moved to a precision
phase of the measurements," says Queen's University Professor Art McDonald, SNO
Project Director through the first two phases of the project. "These
measurements are essential to define a new theory of elementary particles
required to explain finite neutrino masses and their ability to change types.
Some of the simplest proposed theories have already been ruled out."

To accomplish the new measurements, the SNO Collaboration added 2 tonnes of
high-purity table salt (NaCl) to the 1,000 tonnes of heavy water at the heart of
the detector, sited two kilometers underground in Inco's Creighton Mine near
Sudbury, Canada. Two-thirds of the electron-type neutrinos produced by nuclear
reactions in the core of the Sun are observed to change to muon- or tau-type
neutrinos before reaching the Earth. "These new, solid results are obtained with
a 'pinch of salt,' providing three times better sensitivity to the muon and tau
neutrinos," says Tony Noble, Director of the SNO Institute that administers the
project on behalf of an international collaboration of 130 scientists from 15
institutions in Canada, the U.S. and the U.K.

The observations in recent years that neutrinos change from one type to another,
implying that they have mass, has led to great interest in the scientific
community. These new findings require a modification of the most basic theories
for elementary particles and have provided a strong confirmation that our
theories of energy generation in the Sun are very accurate. New experiments to
provide further information on neutrino properties and the origin of the Dark
Matter in the Universe are being developed. These include projects that could be
sited in the new SNOLAB being developed near the SNO underground site. Such
measurements could provide insight into fundamental questions such as why our
Universe is composed of matter rather than anti-matter. The answers to such
questions require a further understanding of elementary particle theory and
further insight into the evolution of the Universe.

To pursue such questions, the Sudbury Neutrino Observatory is about to enter a
third experimental phase with new sensitivity. Says Professor Hamish Robertson
of the University of Washington, Seattle, U.S. Co-spokesman and Interim SNO
Director for this transition phase, "We have developed a half-kilometer-long
array of ultra-clean detectors to be placed in the heavy water after the salt is
removed in September. These detectors are precision instruments that will give
us further insight into neutrino properties."

Nick Jelley of Oxford University, England, co-spokesman of the U.K. SNO
Collaboration states, "As we have moved forward with ever increasing
sensitivity, we are learning more about neutrinos and their place in the
Universe. It is very exciting to be performing these ground-breaking
measurements with our unique experimental sensitivity."

The new results from the Sudbury Neutrino Observatory (SNO) have been submitted
for publication and are posted at
http://www.sno.phy.queensu.ca/
The web site for the TAUP 2003 conference is:
http://int.phys.washington.edu/taup2003/.

Background Information on the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory is a unique neutrino telescope, the size of a
ten-storey building, two kilometers underground in Inco's Creighton Mine near
Sudbury, Ontario, planned, constructed and operated by a 100-member team of
scientists from Canada, the United States and the United Kingdom. Through its
use of heavy water, the SNO detector provides new ways to detect neutrinos from
the sun and other astrophysical objects and measure their properties.

For many years, the number of solar neutrinos measured by other underground
detectors has been found to be smaller than expected from theories of energy
generation in the sun. This had led scientists to infer that either the
understanding of the Sun is incomplete, or that the neutrinos are changing from
one type to another in transit from the core of the Sun.

The SNO detector has the capability to determine whether solar neutrinos are
changing their type en-route to Earth, thus providing answers to questions about
neutrino properties and solar energy generation.

The SNO detector consists of 1000 tonnes of ultra-pure heavy water enclosed in a
12-meter diameter acrylic plastic vessel, which in turn is surrounded by
ultra-pure ordinary water in a giant 22-meter diameter by 34-meter high cavity.
Outside the acrylic vessel is a 17-meter diameter geodesic sphere containing
9,456 light sensors or photomultiplier tubes, which detect tiny flashes of light
emitted as neutrinos are stopped or scattered in the heavy water. The flashes
are recorded and analyzed to extract information about the neutrinos causing
them. At a detection rate on the order of 10 per day, many days of operation are
required to provide sufficient data for a complete analysis. The laboratory
includes electronics and computer facilities, a control room, and water
purification systems for both heavy and regular water.

The construction of the SNO Laboratory began in 1990 and was completed in 1998
at a capital cost of $73M CDN with support from the Natural Sciences and
Engineering Research Council of Canada, the National Research Council of Canada,
the Northern Ontario Heritage Foundation, Industry, Science and Technology
Canada, Inco Limited, the United States Department of Energy, and the Particle
Physics and Astronomy Research Council of the U.K. The heavy water is on loan
from Canada's federal agency AECL with the cooperation of Ontario Power
Generation, and the unique underground location is provided through the
cooperation and support of Inco Limited.

Measurements at the SNO Laboratory began in 1999, and the detector has been in
almost continuous operation since November 1999 when, after a period of
calibration and testing, its operating parameters were set in their final
configuration. Measurements from the initial phase with pure heavy water were
reported in 2001 and 2002 and showed clearly that about two-thirds of the
electron type neutrinos created in the Sun changed their type to muon- or
tau-type neutrinos in transit to the Earth. This transformation appears to arise
from a finite mass for neutrinos, a finding beyond the current Standard Model of
Elementary Particles. The measurements of all three neutrino types showed very
good agreement with the expected numbers of neutrinos generated in the Sun,
confirming current theories of energy generation in the Sun.

Further background information can be found on the SNO website:
http://www.sno.phy.queensu.ca

SNO Participating Institutions

Canada:
Queen's University
Carleton University
Laurentian University
University of Guelph
University of British Columbia
TRIUMF Laboratory

United States:
Lawrence Berkeley National Laboratory
Los Alamos National Laboratory
University of Pennsylvania
University of Washington
Brookhaven National Laboratory
University of Texas, Austin

United Kingdom:
Oxford University
University of Sussex
Rutherford Appleton Laboratory

For further information:

Prof. Art McDonald
SNO Director, on sabbatical
University Research Chair in Physics
Queen's University
Kingston, Ontario
FAX (613) 533-6813


Prof. Tony Noble
SNO Institute Director
Sudbury Neutrino Observatory Institute
Queen's University
Kingston, Ontario
(613) 533-2679
FAX (613) 533-6813


Prof. Doug Hallman
Director of Communications
Sudbury Neutrino Observatory
Laurentian University
Sudbury, Ontario
(705) 675-1151 Ext. 2202
FAX (705) 675-4868


Prof. Hamish Robertson,
US Co-spokesman, Interim SNO Director
University of Washington
Seattle, Washington, USA
(206)616-2745
FAX (206) 616-2902


Prof. Eugene Beier
U.S. Co-spokesman
University of Pennsylvania
Philadelphia, PA, USA
(215) 898-5960
FAX (215) 898-8512


Prof. Nick Jelley
UK Co-spokesman
Oxford University
Oxford, England, UK
011 441 865 273380
FAX: 011 441 865 273418


Prof. David Wark
U.K. Co-spokesman
RAL/University of Sussex
Sussex, UK
011 44 1 235 445094
FAX 011 44 1 235 446733


Prof. David Sinclair
Director of SNOLAB Development
Carleton University
Ottawa, Ont. Canada
613 520-7536
FAX: 613 520-7546


Reference:

Paul de la Riva
Media relations officer
Public Affairs Department
Laurentian University
Sudbury, ON, Canada
(705) 673-6566
www.laurentian.ca


Nancy Dorrance
Public Affairs
Queen's University
Kingston, ON, Canada
(613) 533-2869
FAX (613) 533-6652
www.queensu.ca