<s>
A	O
nuclear	B-Algorithm
emulsion	I-Algorithm
plate	O
is	O
a	O
type	O
of	O
particle	B-Algorithm
detector	I-Algorithm
first	O
used	O
in	O
nuclear	O
and	O
particle	O
physics	O
experiments	O
in	O
the	O
early	O
decades	O
of	O
the	O
20th	O
century	O
.	O
</s>
<s>
It	O
is	O
a	O
modified	O
form	O
of	O
photographic	B-Algorithm
plate	I-Algorithm
that	O
can	O
be	O
used	O
to	O
record	O
and	O
investigate	O
fast	O
charged	O
particles	O
like	O
alpha-particles	O
,	O
nucleons	O
,	O
leptons	O
or	O
mesons	B-Application
.	O
</s>
<s>
The	O
nuclear	B-Algorithm
emulsion	I-Algorithm
plate	O
is	O
a	O
modified	O
form	O
of	O
photographic	B-Algorithm
plate	I-Algorithm
,	O
coated	O
with	O
a	O
thicker	O
photographic	O
emulsion	O
of	O
gelatine	O
containing	O
a	O
higher	O
concentration	O
of	O
very	O
fine	O
silver	O
halide	O
grains	O
;	O
the	O
exact	O
composition	O
of	O
the	O
emulsion	O
being	O
optimised	O
for	O
particle	O
detection	O
.	O
</s>
<s>
It	O
has	O
the	O
advantage	O
of	O
extremely	O
high	O
spatial	O
precision	O
,	O
limited	O
only	O
by	O
the	O
size	O
of	O
the	O
silver	O
halide	O
grains	O
(	O
a	O
few	O
microns	O
)	O
,	O
a	O
precision	O
that	O
surpasses	O
even	O
the	O
best	O
of	O
modern	O
particle	B-Algorithm
detectors	I-Algorithm
(	O
observe	O
the	O
scale	O
in	O
the	O
image	O
below	O
,	O
of	O
K-meson	O
decay	O
)	O
.	O
</s>
<s>
These	O
features	O
were	O
decisive	O
in	O
enabling	O
the	O
high-altitude	O
,	O
mountain	O
and	O
balloon	O
based	O
studies	O
of	O
cosmic	O
rays	O
that	O
led	O
to	O
the	O
discovery	O
of	O
the	O
pi-meson	O
and	O
parity	O
violation	O
in	O
K-meson	O
decays	O
;	O
shedding	O
light	O
on	O
the	O
true	O
nature	O
and	O
extent	O
of	O
the	O
subnuclear	O
"	O
particle	O
zoo	O
"	O
,	O
defining	O
a	O
milestone	O
in	O
the	O
development	O
of	O
modern	O
experimental	O
particle	O
physics	O
.	O
</s>
<s>
The	O
chief	O
disadvantage	O
of	O
nuclear	B-Algorithm
emulsion	I-Algorithm
is	O
that	O
it	O
is	O
a	O
dense	O
and	O
complex	O
material	O
(	O
silver	O
,	O
bromine	O
,	O
carbon	O
,	O
nitrogen	O
,	O
oxygen	O
)	O
which	O
potentially	O
impedes	O
the	O
flight	O
of	O
particles	O
to	O
other	O
detector	O
components	O
through	O
multiple	O
scattering	O
and	O
ionising	O
energy	O
loss	O
.	O
</s>
<s>
These	O
disadvantages	O
,	O
coupled	O
with	O
the	O
emergence	O
of	O
new	O
particle	B-Algorithm
detector	I-Algorithm
and	O
particle	O
accelerator	O
technologies	O
,	O
led	O
to	O
a	O
decline	O
in	O
use	O
of	O
nuclear	B-Algorithm
emulsion	I-Algorithm
plates	O
in	O
particle	O
physics	O
towards	O
the	O
end	O
of	O
the	O
20th	O
century	O
.	O
</s>
<s>
For	O
an	O
extensive	O
review	O
of	O
the	O
history	O
and	O
wider	O
scientific	O
context	O
of	O
the	O
nuclear	B-Algorithm
emulsion	I-Algorithm
method	O
,	O
refer	O
to	O
the	O
book	O
by	O
Galison	O
.	O
</s>
<s>
In	O
1905	O
he	O
was	O
using	O
commercially	O
available	O
photographic	B-Algorithm
plates	I-Algorithm
to	O
continue	O
his	O
research	O
into	O
the	O
properties	O
of	O
the	O
recently	O
discovered	O
alpha	O
rays	O
produced	O
in	O
the	O
radioactive	O
decay	O
of	O
some	O
atomic	O
nuclei	O
.	O
</s>
<s>
This	O
involved	O
analysing	O
the	O
darkening	O
of	O
photographic	B-Algorithm
plates	I-Algorithm
caused	O
by	O
irradiation	O
with	O
the	O
alpha	O
rays	O
.	O
</s>
<s>
After	O
many	O
trials	O
,	O
using	O
different	O
plates	O
and	O
careful	O
shielding	O
of	O
the	O
emulsion	O
from	O
unwanted	O
radiation	O
,	O
she	O
succeeded	O
in	O
making	O
the	O
first	O
ever	O
observation	O
of	O
proton	O
tracks	O
in	O
a	O
nuclear	B-Algorithm
emulsion	I-Algorithm
.	O
</s>
<s>
By	O
an	O
ingenious	O
example	O
of	O
lateral	O
thinking	O
,	O
she	O
applied	O
a	O
similar	O
method	O
to	O
make	O
the	O
first	O
ever	O
‘	O
observation’	O
of	O
a	O
neutron	O
in	O
nuclear	B-Algorithm
emulsion	I-Algorithm
.	O
</s>
<s>
In	O
1937	O
,	O
Marietta	O
Blau	O
and	O
her	O
former	O
student	O
Hertha	O
Wambacher	O
discovered	O
nuclear	O
disintegration	O
stars	O
(	O
Zertrümmerungsterne	O
)	O
due	O
to	O
spallation	O
in	O
nuclear	B-Algorithm
emulsions	I-Algorithm
that	O
had	O
been	O
exposed	O
to	O
cosmic	O
radiation	O
at	O
a	O
height	O
of	O
2300m	O
on	O
the	O
Hafelekarspitze	O
above	O
Innsbruck	O
.	O
</s>
<s>
This	O
discovery	O
caused	O
a	O
sensation	O
in	O
the	O
world	O
of	O
nuclear	O
and	O
cosmic	O
ray	O
physics	O
,	O
which	O
brought	O
the	O
nuclear	B-Algorithm
emulsion	I-Algorithm
method	O
to	O
the	O
attention	O
of	O
a	O
wider	O
audience	O
.	O
</s>
<s>
Ilford	O
produced	O
a	O
concentrated	O
‘	O
nuclear-research	O
’	O
emulsion	O
containing	O
eight	O
times	O
the	O
normal	O
amount	O
of	O
silver	O
bromide	O
per	O
unit	O
volume	O
(	O
see	O
External	O
Link	O
to	O
'	O
Nuclear	B-Algorithm
emulsions	I-Algorithm
by	O
Ilford	O
 '	O
)	O
.	O
</s>
<s>
First	O
,	O
in	O
1947	O
Cecil	O
Powell	O
,	O
César	O
Lattes	O
,	O
Giuseppe	O
Occhialini	O
and	O
Hugh	O
Muirhead	O
(	O
University	O
of	O
Bristol	O
)	O
,	O
using	O
plates	O
exposed	O
to	O
cosmic	O
rays	O
at	O
the	O
Pic	O
du	O
Midi	O
Observatory	O
in	O
the	O
Pyrenees	O
and	O
scanned	O
by	O
Irene	O
Roberts	O
and	O
Marietta	O
Kurz	O
,	O
discovered	O
the	O
charged	O
Pi-meson	O
.	O
</s>
<s>
Second	O
,	O
two	O
years	O
later	O
In	O
1949	O
,	O
analysing	O
plates	O
exposed	O
at	O
the	O
Sphinx	O
Observatory	O
on	O
the	O
Jungfraujoch	O
in	O
Switzerland	O
,	O
first	O
precise	O
observations	O
of	O
the	O
positive	O
K-meson	O
and	O
its	O
‘	O
strange’	O
decays	O
were	O
made	O
by	O
Rosemary	O
Brown	O
,	O
a	O
research	O
student	O
in	O
Cecil	O
Powell	O
’s	O
group	O
at	O
Bristol	O
.	O
</s>
<s>
Then	O
known	O
as	O
the	O
‘	O
Tau	O
meson’	O
in	O
the	O
Tau-theta	O
puzzle	O
,	O
precise	O
measurement	O
of	O
these	O
K-meson	O
decay	O
modes	O
led	O
to	O
the	O
introduction	O
of	O
the	O
quantum	O
concept	O
of	O
Strangeness	O
and	O
to	O
the	O
discovery	O
of	O
Parity	O
violation	O
in	O
the	O
weak	O
interaction	O
.	O
</s>
<s>
Rosemary	O
Brown	O
called	O
the	O
striking	O
four-track	O
emulsion	O
image	O
,	O
of	O
one	O
'	O
Tau	O
 '	O
decaying	O
to	O
three	O
charged	O
pions	O
,	O
her	O
"	O
K	O
track	O
"	O
,	O
thus	O
effectively	O
naming	O
the	O
newly	O
discovered	O
‘	O
strange’	O
K-meson	O
.	O
</s>
<s>
Cecil	O
Powell	O
was	O
awarded	O
the	O
1950	O
Nobel	O
Prize	O
in	O
Physics	O
"	O
for	O
his	O
development	O
of	O
the	O
photographic	O
method	O
of	O
studying	O
nuclear	O
processes	O
and	O
his	O
discoveries	O
regarding	O
mesons	B-Application
made	O
with	O
this	O
method	O
"	O
.	O
</s>
<s>
The	O
emergence	O
of	O
new	O
particle	B-Algorithm
detector	I-Algorithm
and	O
particle	O
accelerator	O
technologies	O
,	O
coupled	O
with	O
the	O
disadvantages	O
noted	O
in	O
the	O
introduction	O
,	O
led	O
to	O
a	O
decline	O
in	O
use	O
of	O
Nuclear	B-Algorithm
Emulsion	I-Algorithm
plates	O
in	O
Particle	O
Physics	O
towards	O
the	O
end	O
of	O
the	O
20th	O
century	O
.	O
</s>
<s>
More	O
recently	O
,	O
searches	O
for	O
"	O
Physics	O
beyond	O
the	O
Standard	O
Model	O
"	O
,	O
in	O
particular	O
the	O
study	O
of	O
neutrinos	O
and	O
dark	B-Application
matter	I-Application
in	O
their	O
exceedingly	O
rare	O
interactions	O
with	O
normal	O
matter	O
,	O
have	O
led	O
to	O
a	O
revival	O
of	O
the	O
technique	O
.	O
</s>
<s>
There	O
exist	O
a	O
number	O
of	O
scientific	O
and	O
technical	O
fields	O
where	O
the	O
ability	O
of	O
nuclear	B-Algorithm
emulsion	I-Algorithm
to	O
accurately	O
record	O
the	O
position	O
,	O
direction	O
and	O
energy	O
of	O
electrically	O
charged	O
particles	O
,	O
or	O
to	O
integrate	O
their	O
effect	O
,	O
has	O
found	O
application	O
.	O
</s>
