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Martin L. Perl, Valerie Halyo, Peter C. Kim,
Eric R. Lee, Irwin T. Lee, and Dinesh Loomba
Stanford Linear Accelerator Center
Stanford University
Stanford, CA 94306
THE SEARCH FOR
FRACTIONAL CHARGE PARTICLES
AND
VERY MASSIVE PARTICLES
IN
BULK MATTER
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Part 1
FREE FRACTIONAL CHARGE
ELEMENTARY PARTICLES
fUse to denote a fractional charge particle
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SEARCH METHODS FOR
FREE FRACTIONAL CHARGE
ELEMENTARY PARTICLES
FFFFCosmic Rays :
FFBulk Matter :
FFFF Accelerators: Straightforward butlimited in mass anduncertain in productioncross section.
Worth trying but
limited in mass and
uncertain in production
process.
General method,
dependent upon productionin early universe. Very
large mass range. Our
preference.
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FROM EARLY UNIVERSE TO
SOLAR SYSTEM
space
solar system
early universe
star
f
f f
f
f
f f
f
fX
f fY
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FRACTIONAL CHARGE PARTICLES
CHANGE THE CHEMISTRY OF
ATOMS AND MOLECULES
For example, a hydrogen atom with an
additional +1/3 f attached to the nucleushas chemical properties similar to fluorine.
It is similar to a helium atom with a -1/3 f in
a close orbit.*
Therefore the significance of searches in
bulk matter depends upon the chemical and
refining processing history of the material,
including geochemical processes.
*K. S. Lackner and G. Zweig, Phys. Rev. D 28, 1671 (1983);
K. S. Lackner and G. Zweig, Novel Results in Particle Physics
(Am. Inst. Phys., New York,1982)
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FFFFEarth: Accessible now but geochemical
processing must be considered.
Some ancient minerals of great
interest.
FF
Meteorites from asteroids : Great interest
because come from mostprimitive material in solar system.
FF Moon : Some special interest butsamples scarce.
WHERE TO SEARCH FOR
FRACTIONAL CHARGE PARTICLESIN SOLAR SYSTEM
FFFFAsteroids: Best search material, either
bring back large samples or
carry out searches on asteroid.
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SEARCH METHODS IN
BULK MATTER
FFFFLiquid Drop: The method we use; based
on the original Millikan oil
drop method. The material
may be a liquid, a solution,
or a suspension of
a mineral or otherpowder in a liquid. Will
describe next.
FFFF
Levitometer: Suspend a ball of
material usingferromagnetism or
superconductivity. Measure
charge by oscillation in
electric field.
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OUR ORIGINAL
LIQUID DROP METHOD
Drop
generator
Falling drop already
measured
Falling drop just
produced
Trajectory of falling
drop being
measured
Upper electric
plate
Lower electric
plate
Stroboscopic light
source, flashes att intervals.
Vertical E field
alternating in
direction
Lens
CCD face of
video camera.
Area of CCD
sets field of
view of drops
Image of
trajectory of
falling drop
.
Use drops with diameters from 5 to 15 m
Once drop generator is set, diameter is constant to 0.1 %
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PHYSICS OF ORIGINAL
LIQUID DROP METHOD
Force=6rVterm
Stokes Law
Vterm = terminal velocity =viscosity of air
r = radius of drop
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We determine q and m from:
mg +qE down= 6 rVterm,down
mg - qEup = 6 rVterm,up
r = drop radius
q =drop electric charge
g = acceleration of gravity
Eup = electric field when pointed up
Edown
= electric field when pointed u
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PUBLISHED RESULTS OF
LEVITOMETER AND
LIQUID DROP SEARCHESIN BULK MATTER
Method Experiment Material Sample
Mass (mg)
superconducting LaRue et al. niobium 1.1
levitometer
Marinelliet al. iron 3.7
ferromagnetic Smith et al. niobium 4.9
levitometerJones et al. meteorite 2.8
Joyce et al. sea water 0.05
liquid drop Savage et al. mercury 2.0
Maret al. silicone oil 1.1
No fractional charges claimed except by LaRue et al. Their
claim NOT confirmed by Smith et al.
1 mg = 6_1020 nucleons
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OUR NEW UNPUBLISHED
SEARCH IN SILICONE OIL
We have just concluded a search through
17 mg of silicone oil. This used 4.1_107
drops of about 10 mm diameter. The charge
of each drop was measured with a precisionof 1/40 of an electron charge.
We found no evidence for fractional charge
particles but there is a data point thatargues for repeating the experiment with a
larger sample.
For details see:
V. Halyo et al., SLAC-PUB-8283Submitted to Phys.Rev.Lett.
e-Print Archive: hep-ex/9910064
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COMMENTS ON THESE SEARCHES
AND NEXT SEARCHES
$$$$The silicone oil results will be repeated
with a larger sample.
$$ But the major next step is to studyunrefined materials particularly
meteorites. We have samples of theAllende meteorite.
$$ We will also study fluoraptite, amineral that collects fluorine-like
elements.
$$ Sample sizes will be increased.
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Dropgenerator
Vertical electric
plates giving
horizontal electric
field, E
Laminar air flow to reduce
vertical terminal velocity
of large drops so that they
remain in the measuring
region
OUR NEW
HORIZONTAL ELECTRIC FIELDLIQUID DROP METHOD
Uses much larger drops: 20 to 100 m diameter
qE = 6rVterm,horizontal
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%%%% Increase sample sizes fromtens of milligrams to tens
of grams or even a kilogram.
%%%% Bring large samples from
asteroids or put searchapparatus on asteroid.
TWENTY FIVE YEAR GOALS FOR
FRACTIONAL CHARGE PARTICLESEARCH
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Part 2
VERY MASSIVE AND STABLE
ELEMENTARY PARTICLES
Consider very massive particle:
tttt produced in early universe,
tttt stable,
tttt charged or bound to charged particle, and
tttt present in solar system.
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LIQUID DROP SEARCH METHOD
FORVERY MASSIVE PARTICLES
1 GeV/c2 = 1.8 10-24 grams
Mass of 5 m diameter drop = 10-10 grams
therefore
Mass of 5 m diameter drop is about
5 1013 GeV/c2
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Force=6rVterm
Stokes Law again:
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Drop of mass m falling in air:
Vterm(m) = mg/(6r
Drop of mass m falling containingan elementary particle of mass M
falling in air:
Vterm
(m+M) = (m+M)g/(6r)
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v
v(m) v(m+M)
logdN/dV
falling dropbeing measured
stroboscopic
light source
CCD face of video
camera used to
measure terminal
velocity and drop
radius via imaging
drop
imaginglens
drop generator
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The lower mass search limit is set by the
mass of the smallest mass drops that can
be used in a practical search and by the
extent of the tails on the v(m) peak.
The lower mass search limit is between
1013 and 1014 GeV/c2
LOWER MASS LIMIT ON SEARCH
FORVERY MASSIVE PARTICLES
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UPPER MASS LIMIT ON SEARCH
FORVERY MASSIVE PARTICLES
The upper mass search limit is set by the
requirement that the massive particle beheld in ordinary matter by the Coulomb
force Fc between the particles charge
and the nearby atoms. Estimate
Fc = 1 eV/10-10 m = 1.6_10-9nt
On the Earths surface require: Mg < Fc.
Therefore the upper mass limit on the
Earth is:
M < 1.6_10-10kg = 1017 GeV/c2
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SEARCHING FOR VERY MASSIVE
PARTICLES IN METEORITES
$$$$ Searching for very massive particlesin terrestrial minerals is chancy
because of the geological history of
the earth.
$$$$ The best materials for very massiveparticle searches are meteorites. We
have samples of the Allende meteorite.
$$$$ But there is a problem with the uppermass limit when searching in
meteorites. When meteorites enter the
atmosphere and slow down the
deceleration force may be 100g to
1000g. Therefore the more massive
particles will not stay in the meteorite.
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%%%% Develop experimental
method by searching inmeteorites and other
minerals on Earth.
%%%% Send the search apparatusto an asteroid and search
on the asteroid. There are
many advantages includinga larger search range since
gasteroid
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