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Author(s)
Tullington, Bernard John Jr
Title
The excitation of helium by high energy proton bombardment at various pressures.
Publisher
Monterey, California. Naval Postgraduate School
Issue Date
1968-06
URL
http://hdl.handle.net/10945/28197
This document was downloaded on February 04, 2015 at 16:17:47
UNITED STATES
NAVAL POSTGRADUATE SCHOOL
THESIS
THE EXCITATION OF HELIUM BY HIGH ENERGY
PROTON BOMBARDMENT
AT'
VARIOUS PRESSURES
by
Bernard John Tullington, Jr
June 1968
T924
special expro
in
govern
onlv with
'tn^S.
NavaV Postgraduate
S
Postgraduate schooe
THE EXCITATION OF HELIUM
BY HIGH ENERGY PROTON BOMBARDMENT
AT VARIOUS PRESSURES
by
Bernard John Tullington, Jr.
Major, United States Army
Military Academy, 1957
B.S.
,
Submitted in partial fulfillment of the
requirements for the degree of
MASTER OF SCIENCE IN PHYSICS
from the
NAVAL POSTGRADUATE SCHOOL
June 1968
KkD
ABSTRACT
The intensities of several helium spectral lines are analyzed
for their dependence on pressure.
Neutral helium was bombarded by
protons, accelerated in a Van de Graaff generator to energies of
1.6 MeV before they passed through an aluminum foil window into the
collision chamber.
Eight helium emission lines and one nitrogen
line (impurity) were detected by photographic analysis of the
collision spectrum at various pressures.
Relative intensities of
five of the helium emission lines were measured with photoelectric
apparatus at pressures from 10
-
550 Torr
.
Lines of 6678A, 728lA,
7065A and 5876A show a similiar, but not exact, functional dependence on pressure.
The 3889X line appears to have
a
quite different
pressure dependence that may possibly be due to the nitorgen impurity.
Suggested experimental improvements are discussed.
•
TABLE OF CONTENTS
SUBJECT
Page Number
Abs
2
1
i
List of Illustrations
5
Ac know edgm<
6
J
i
1
1
B.i
1
'
t
i
ion
7
kgr ound
9
Experimental Procedu
13
He
13
I
i
urn
Coll is ion Spectrum
r
ul1
R)
Surama
Bib]
In
i
1
i
i
2]
<
a
24
v
l
59
»
I
DD Form
Distr ibut on
i
]
•
I
ko
4i
LIST OF ILLUSTRATIONS
Figure Number
Page Number
1.
Top View of Collision Chamber
16
2.
Schematic of Gaertner Spectrometer Optical
System
16
3.
\y
-
States Diagram for Helium
l8
4.
Schematic for Optical Apparatus
5.
Graph,
Intensity vs Pressure; 6678A
26
6.
Graph,
Intensity vs Pressure; 728lA*
27
7.
Graph,
Intensity vs Pressure; 3889$
28
8.
Graph,
Intensity vs Pressure; 5876A
29
').
Graph,
Intensity vs Pressure; 7065A
30
20
1<).
Graph, Pressure/Intensity vs Pressure; 6678A
31
11.
Graph, Pressure/Intensity vs Pressure; 7281X
32
12.
Graph, Pressure/Intensity vs Pressure; 7°65A
33
13.
i.Mjih,
Pressure/Intensity vs Pressure; 5876A
34
14.
Graph, Pressure/Intensity vs Pressure; 3889A
35
15.
Photograph. Drift tube, collision chamber and
control manifold
36
16.
Photograph. Optical equipment in position
37
17.
Photograph. Control console and measuring
devices
38
.
ACKNOWLEDGEMENTS
The writer wishes to express his appreciation for the continuous assistance and encouragement given him by Professor
E.A. Milne in this investigation, as well as to Professor
R.L. Kelly for his assistance in the photographic and optical
aspects of the apparatus; and to Mr. Ray Garcia who provided
technical assistance in the maintenance of the electronic equipment and Van de Graaff accelerator
This project was supported in part by funds provided by
the Naval Ordnance Laboratory.
.
.
I.
INTRODUCTION
The processes by which excited states of helium are formed
by
ion-atom impact have been the subject of an increasing number
oi
studies.
These studies have progressively extended the pro-
jectile energy range from earlier investigations of less than
200 keV to
Lmpo]
able
-i.
h
i
t
While these investigations are of fundamental
determining excitation cross sections and are valu-
n
i
verifyii
in
ba
MeV.
1
ed primarily on the simplifying assumption of the single
cond
i
t
i
on
The single hit
independent
Lty.
is
I
t
ion assumes an excitation cross section
nd thus demands a very low target
oi
particle
experimental procedure (under this assumption)
he norm.*]
the coll ision t.ike place in a differentially pumped
to have
undei
hunboi
<
predictions at high energies, they
I
pi e
Emission cro
in es
>ns
in
(or
the region of 10
-4
or
10
-5
Torr
.
apparent cross sections as they are
sometimes called) are then measured over a limited pressure range.
li
the emission cross
pressure,
a
section
the single hit
pressure dependence
is
is
found not to be dependent on
condition is assumed to be satisfied.
noted, as is often the case,
If
the procedure
been either to operate in so called regions of non-dependence
or
to extiapolate the emission cross section to zero pressure and
use tha
t
va] ue
The next step in better understanding the excitation process
is
obvious.
11
the single hit condition is not satisfied, what are
the processes leading to the formation of the excited states of
n
.
helium?
A starting point in answering this question is an under-
standing of the pressure dependence, if any, of the emission cross
sections.
Five helium spectral lines are observed as
a
function
of pressure representing both para (singlet) and ortho (triplet)
trans it ions
;
I
I
BACKGROUND
.
Neutral Helium may be excited by proton bombardment by direct
exci tat on
i
+
H
H
=
+
He(n,l)
charge transfer;
or by
+
H
or
+
He
+
He
+
by simultaneous
H
=
+
He (n,l)
+
ionization and excitation;
He
*
H
-
H
+
He (n,l)
+ e~
Once excited, He(n,l) may fall to
ground
co]
1
is
.
i
ona
tr
I
radiative decay,
or
it
a
metastable state
or
may be de-excited by
ansj
The rate of change of the population density of any state
may be wr
dN
i
t
t
i
en
.
—_!
= nv Na
<lt
.
1
+ S
k>
A
i
N,
.
k1
k
S
j
-
i
A..N.
+C.(n,N.V)
T
x
x
(1)
J
The first term on the right expresses the rate of collisional
population
(v),
in
terms of projectile density (n), projectile velocity
target density N and the excitation cross section a..
second term provides for population of the
states
from all
bility
term is
A.
K
a
.
k
higher than
i,
in terms
i
The
state by cascade
'
of the transition proba-
and the population density of state
k,
(
N,
)
The third
.
K.
1
measure of the rate at which state
iiative decay from state
i
to all states
terms of transition probability
A.
r
.
XJ
j
i
is
depopulated by
lower than
i,
and state density N..
also in
The last
1
term of equation (1) represents secondary processes such as collisional depopulation,
collisional transfer and population by absorp-
tion of resonance photons.
Gabriel and Heddle 3 have developed
a
technique for determining the value of this function under single
For brevity
hit conditions by a method of simultaneous solutions.
it
is shown here simply as a
possible function of
n,
v,
and N.
state conditions,
For steady
dN.
dT
Equation
1
0.
s
can be solved for a
o
^
nvN
A. .N.
j< i xj
-
1
.
T,
k>i
and
A,
is
-N,
ki k
-
C. (n,v,N)
(2
9
The normal development which follows is to define an
emission cross section in terms of the number of photons emitted/
sec/ cm of beam path, J.
as
.,
xj
IJ
u
NI
ij
(3)
'
where N is the number density of the target,
I
=
nv A, the number
of incident projectiles per second, A the beam cross sectional
area, and J.
= A. .N.A.
xj x
.
ij
Equation
is
3
now
A. .N.
(4)
Nnv
ij
the cross sectional area cancelling out.
Making the appropriate substitution, equation
a
=
.
1
where
C
= C( n
,
a
j<i !J
T,
.
.
-
T,
a.+c',
k>i ki
v,N)/nvN.
10
(2)
now becomes
(5)
some specific state
For
emission
i
->
transition may be related to the total photon emission
1
downward transitions by
by all
J.
A.
n
Relal ing equal Lons
.
i
i
into e q u
c
—
A
l
j-i
'J
i
a.
t,
t:
pi
(lower than i), the intensity of the
1
and (6) and substituting where appro-
3)
(
(6)
.
j
I
—
A
S
S
k>
-
il
km A
*
cond term on the right
i
into
itten
In
t hi
«i
I
ed
i
related to the total
bil it ie
This
.
is
*
Standards
in
C
(7)
.
the cascade correction and
to show all
emission functions
Any emission out of state m can be
.
for tunate,
as
the transition pr obabil it ies for
been tabulated by the Bureau of
ha^
1()
,
,
It
is
now
ous
thai
knowing J.,
i
will
+
km
emission through the ratio of transition proba-
helium are well known and
<
te
I
is
.
for
only
a
few transitions
1
Lead to the deter mi nat ion of the excitation cross section
ff.,
i
•e
The photoele<
sol id angle &
nog ec ed
1
ti ic
=
ij
L
is
.
apparatus will accept photons through a
and will deliver
j
where
t
a
signal S.
.
by the relationship
iJ
A^_
L K(X
(
K
)
8)
'
the beam length and K(X) is a dimensionless factor which
takes into account the systems detection sensitivity and losses due
to refraction and reflection at optical surfaces.
1
I
una!
'
.
filament Lam]
observed.
ivhe>
ll
For
the collision is
coi
lamp at the wavelength of
the
i
om a standard
consideration,
the wavelength under
i
fi
A.
interest,
d the spe<
optical
the inverse dispersion of the spectrometer
D,
exit slil
ter
-
system,
may be determi]
E,
which may be measured by
I
ds
(9)
*
for
KfA
J.
=
j
•
pyrometer
a
furnished by the manufa
Solving
wl.
(A/mm),
the area viewed by the
on the filament
if this
information
temperature
is
not
.
and substituting into equation (8)
j
S.
.
4"
.
-~3-
E.
dw
D,
(10)
Thus, under single hit conditions, where
of N, and C' can be ignored,
cr
.
_
il
is
not a function
the excitation cross section can
readily be determined by measuring
0"
.
,
as;
1
i
It
1
'
S
NI
*
should be
collision patn
ther
.
the so
need be measured undea
'
i
;he
conditions.
.
EXPERIMENTAL PROCEDURES
III.
From section II,
may be wr
(II)
i
independent of pressure, equation
is
i
as
It ten
P = C" R
(12)
K
4
T
.
n
I
ill'
"1
.
1
1
I*
apparatus
i
S.
V
*
I
beam current which is measured by the
the target pressure,
P,
.
by the
A plot
dwN kT
measure of the photon emission intensity
-I
)
to the photon
Lve
^
./]
S
R
r).
idea]
gas
l.iw,
line with a slope of C",
itraight
related to the
PV = N kT
sure should result
rntensity versu
ni
is
if
is
.
in
a
independent of pressure.
THE HELIUM COLLISION SPECTRUM
proton beam was produced by
part icle acceleratoi
and
.(i
x
1
(
used
cm)
)
the coll Lsion chamber.
,n nl
\
I
L1
the coll
apparatus
in
Fig.
is
LO
a
magnet which bends
A thin aluminum foil,
.
pa rate the particle dr if t
1
(about
tube
fr
om
The collision chamber was constructed of
A
is ion
.5 cm
quartz lens,
(f = 16.3 cm)
was used
spectrum on the optical apparatus.
shown schematically
in
Fig.
1
This
and photographically
15.
Mid way
b<
tween the collision chamber and viewing lens is the
vacuum manifold (below) and
linn
MeV Van de Graaff
ted wi th an aluminum far a day cup to measure the pro-
ton beam current.
to focus
2
analyzed by
ma:
the beam through an angle of
1
a
gas control manifold (above).
a
-vstem, consisting of a
13
2
The
inch oil diffusion pump, backed
.
fore pump, Was capable of evacuating the chamber to
up by
4 x
.
Torr
10
The control
.
manifold provided
collision chamber, (numbered
Ln
Pig.
1).
5
inlets into the
The ports were used for;
to 50 Torr pressure gauge;
(1)
gas
inlet;
(2)
Wallace riernan,
(3)
ion gauge;
(4)
fore pump; and (5) a mercury monometer
The beam was viewed at 90
to
1
»
he collision chamber by the
optical apparatus,
To determine the purify of the target gas,
was photographed
t>y
shown schematically
a
the collision beam
large Gaertnei L254 Quartz spectrometer,
Ln
This spectrometer provides photo-
Fig, 2.
graphic coverage from 1900A to 8000A, on photographic plates
4 x 10
inches
Numerous unsuccessful attempts were made to obtain
scopically pure helium photograph.
a
spectro-
These attempts included water
pumped commercial helium and vapor from liquid helium.
These pro-
cedures led to spectrographs of primarily nitrogen and some other
impurities but no helium lines were evident.
The most satisfactory procedure was to pump the system for
several hours, saturate
prior
to
a
L1
with research grade helium and repump
<
Research grade helium (rated single impurities of
2
parts per
million of neon by the manufacturer) was used and the tank was
connected directly through
a
Even with this procedure
single Nitrogen line (39l4A) was still
a
gas regulator
evident at pressures above 50 Torr,
i
4
to the inlet manifold:
-
Photographs
200 Torr, and
L.65 M<-V.
general,
,
1
1
/
I
pressures
at
i
re
1
wa
ii
e
ul t s
f 01
<
1
tor
[n<
.
intensity bu1
1
I
I
f
(
Beam currents uf
1
.
'5
to 3 hours.
B<
1
rent
Lnci ea
th<
the
e
-
result
and higher
very
In
tl
ned from
'
'
nvelen
•<
rhe line:
d
i
w th the
i
h\
th<
trans it ions
Ol
Pho
H<
togi
-
and 103F
,\
which
N
designed
is
Listed in Table
from the pla
ii
[ .
I
.
Lagr am
Table
lower
Intensity would be
on Kodak emulsion
plates.
In
times at
ex]
-
Ml
i
,
.
bee,
It
I
from
vai Led
Lm<
orr
:
indicated particle energy
,in
E
of
with udrying results.
i
roamp
mi<
oi
w<
Lum Spectral
ma] ys i s
,
in
and they
Fig.
11
I
own
i
Line
Tr ansi
Waveleng
A
hV
-
<V
2^p
1.6
3
-
!
3
3
.
I
9
i
D
S
L
P
It
I
ions
should be
feJ
.'
I
•
the opticall]
range of the op1
1
5
•
1
1
owed
1.
tr
equipm*
Ltf$
MANJfOCO
\/AQUUN\
g£Aiv\
SYSTEM
D£f\f\JiW6
5LITS
J CM
Diffusion
Figure
1.
pump
Top view of collision chamber showing the
relative positions of the drift tube, vacuum
system and control manifold
BEtfNN
Figure 2.
Schematic representation of the Gaertner
L254 Quartz Spectrometer Optical System
16
.
.
INTENSITY VS PRESSURE
The helium gas was let in through
roughly
rorr
Mm
from
0.2
a
The beam wa
.
colli
monochrometer
eel Ash
I
ect
1
t
Led
hi
r
101
I'M
tomul
ph
!
to pass
t
ipl
en1
1
>
1
>m
t
1
entrance
current
t
with
covered,
integi itoi
ime
lected
shows
si it
r
a
Figures
equ ir ed
schema
Lb
,
1
rhe
ill
1
>hot
(negative).
o a
cur
recorded.
r
en
t
omul t
re
1
-
ipl
um
The output
integr
The ent
a
ir e
t
or
opt ica
1
black cloth to reduce the amount
1
With the
500 micr ocoul ombs
ect ion and the total
charge col-
integrator were recorded.
photographs of
I
.
t
Figure k
set-up.
he appar a tus
ted divided by time was
taken to be the
This value multiplied by the time for
subsequent
ubtracted from the photomul t ipl ier output.
Lnit Lai
data wer<
taken with the diffusion pump engaged
This was considered to be the zero
and the entrance slit exposed.
I
wa
t
f
tat ion of the photoelectrical
repi
rhe charge thu
1
a
went
A
.
allowed to accumulate
wa
foj
L<
and
dark current.
mbly
the beam was again turned on and the beam
the photomultipl
l>v
er
dry-ice-
ed wavelength to a
1250 volts
i
The monochro-
.
while the chamber was again evacuated.
Light
is
was necessary to use wider
•
1
ted
embly was th
tray
th<
iei
ipl
where the total
rhe
it
,
tube was used and operated a1
cur
The monochr ometer
.
which greatly reduced this resolving power
si its
Light
of wavelengths from 1"500a to 9000A + 10A.
ight
Intensities,
low
admitted into the chamber.
th< n
region was focused onto the entrance slit of
Lon
mi
>
to a pressure of about
ision chamber
i
needle valve into the
a
readings.
beam
w
is
turned on from the control console,
$0
Pj
^2
^
$
t
Pz ,l
^7,1
^,3,2.
24-
4
T
3965
2.3
Z2
Z)
3883
ZO
eV
Figure
3.
Energy-states diagram for photographically
detected He spectrum lines by H + bombardment
18
This automatically activated the timti
Fig. 17).
rent
integrator and phot omu
sele<
t(
Lomb
''-II
sure
Intervals
1
am
ol
Torr.
'60
remained
d
(
ai-,
i
did no1
i
t
I
aboul
,i
n
was observed that the dark current would
It
<
time span of about
t
he phot omul
this phenomenon.
constanl
a
a
2
hours.
rose rapidly and could no longer be
I
Repacking
altei
maximum
Intervals to reduce the effect of the
r
.
l
a
Subsequent runs
500 Torr.
J00 or
proved to be unsui
so
for
Lme
i
Pres-
were initially selected up to 50 Torr,
entiallj
the dark
cou-
was found that the intensity behavior
11
frequent
that,
At each
time, photomult ipl ier
intervals were selected up to
hanging dark current.
beam cur-
oulomb collection were recorded.
i
after
n1
(
or
I
mvenienl
ol
i
Aitti
current integrator.
ipl ier
the he] ium pressure,
then varii
<
t
,
t
as -embly with dr y
ipl ier
Cooling by liquid nitrogen
lul
in
prolonging the effective
dark current.
Prom the data collected as described above, the transition
intensity was computed
R
where Ph
i
t
Five
by this
to the
si its
lines.
and
1
H
1
(13)
=
dark current,
Lected by the beam integrator.
Lnes observed by the photographic analysis were measured
technique.
Low
DC x t)/B;
-
charge colle< ted via P.M. assembly, DC
-
Lme,
(Ph
Lntensil
Et
impossible to study
was
involved.
than those provided
in
It
,K
of the lines due
was even necessary to use wider
the monochr ometer to study the five
The monochr omet er has standard slits of
used were about
3
mm wide.
L9
.1
mm,
The slits
csr
C£
p
O
UJ
Q-£
hZ
Figure
<
CD
h-
4.
Cfc^
Ui ^>
H-*
^-
2
Schematic of optical apparatus for irtensity
vs. pressure measurements
20
N
RESULTS AND CONCLUSIONS
iV.
[ntensil
bed above were measured vs pressure for
i<
the singlel
triplel
the
P
-
s
/S89X (2 S
-
s
a
(2
3
Lin
A plot
hown
i
n
;
-
f
1
nglel
lun<
ol
lowed by
conl
i
Lplet
loii
LOO
.
n<
ioned
\
oi
ivhii h
e
then
ni
1
It
1
s
functional
is
1
1
behavioi
rapidly increases up to
t
levelling off effect.
This
rise in in tens ity to the
r
singlet lines
2
ises rapidly dur ing the fir st
line has a slight sigmoidal tend-
i
The 587b line indicates a very rapid
.
reaching
it--
near maximum at about 25 Tori
and
nth pressure similar to the other lines
obvious from
dep<
e
to
ted to hold at
similar
uenc ng factors are possibly responsible
1
slight
a
which
S89
.
intensity,
in
a
Lso
sug
iai
and
D)
show no such functional similarity
1
1
pr<
pecu]
3
and
,
ndicated.
tran
.
3
-
S)
3
to have a
similar to the
I
-
respectively.
9
gene]
tin
foi
t
and
•.
maximum pre
ti
(2 P
1
P
intensity vs pressure for these lines
they undergo
a
(2
3
5876$
P),
1
7281$
tens it its appear
'1
loir
LOO
1
3
depend
ionaj
1
8
7,
,
.
:
of
D) and
curves that there is, indeed,
1
a
the emission cross sections on pressure
oi
The single hit condition
i.
hardly ex-
is
these high pressures.
I
7
i
l
'
—
A
-
•
k>i
:l
km
km
A
-
C
i
» (
l
.
a.
j<i ij
y,
.
(14)
,
as a function of N.
t
c
i
this experiment the
[n
velocity and projectile density were held relatively constant.
In fact,
for a given emission i—»1, all of the terms are constant
except C'(N), and equation (14) may be written as;
*
±1
A
=
xg-ii—
C»(N)
-
(15)
.
U
j<i
Equation (12) may be written as;
°
±1
D
=
-
(f)
A and D in equation (15) and
C'(N) a C (P).
!
(
Equating (15) to
R
D(|)
(
16
yields,
)
A
C'(P) x
- A
)
Since N ^ P
are constants.
(1.6)
l6
il
g-2^—
(17)
•
j<i ij
Substituting from equation
(6)
and multiplying both sides
by P/R yields:
Xl
x (|)
C'(P) x ^
T
ij
j<i
D = Ax(|)
From equation (10), J.,
experiment
is
<*
held constant.
S
.
.,
,
and
R
=
(18)
.
S.,/l, where
For any given emission, S
i
be a constant
either
oi
a
function of pressure, P
.
in this
1
ll
J.
i
.
will
xJ
Equation (l8)
can now be written a
D = A(|)
|
where /(P)
'
.
i
Is
-
/(P)
-
/(P) x E,
x E
f
+ D»,
some unknown function
tan ts absorbing
v
—
A
.
or
(19)
oi
pressure, and E' and D
f
t
I
data shown
The
P/R vs P.
plol
pendent
equa
i
I
in.
i
[f o
on pr<
ons
Lg
\'
5,
6,
7,
and 9, were used to
8,
the quantity of interest,
.
,
Figs.
in
singly de-
is
vs. P should plot as a straight line from
/U
(
LO,
•
i
I
J
L2
,
,
I
and
},
1
k show the
r
esul ts of this
nipulal
The two singlel
funct iona]
dep<
it
1
tially
aboul
curvi
hough the sharp
till
ther<
curvi
,1
1
to about
up
.
t
vhi ch
(
(3914a)
r
may
is
n
.
eai
1
rgy
rhi
4 () Tor
r
after wh ich
i
ier
a
si ight ly
deer ea s ng
in
be explained by
Section III.
is
i
a
very
dr op
the nitrogen
17.6 eV, which
It
Is
pro]
I
that
as
This
is
14.5 eV
is
roughly equal
energy of helium (about 19.7 eV
•
in
The nitrogen line
required to ionize N
to thi
h.t s
1
The appar ently sudden
Ly
fA
Fig. 3)
.
p
Ler
1
The 7065 line
The ^889 line shows
el at ions hip
abi
commented on
Lmpui ity
se not ed ear
slight bow in the curve.
a
exhibits
it
e.
funct iona]
Intensity
i
the 5876 line is linear up to
ly.
i
with
pecul iai
r
ight uniformity.
Lneai
I
|.ii,
!0
I
t
Lplel
apj
.in
8A and 728lA, again show a similar
i
,
out,
d
rhe
I
.
,
the density of helium atoms
from
m
Increases, more are available to transfer
the metastabl<
tate
then energy
relatively few nitrogen atoms in the collision
chamber.
in
This hypothesis
intensity
Intensity
to the
vs
oJ
is
also indicated by the apparent rise
the nitrogen line on the photographic plates.
pressure
m<
aents were made of the nitrogen
23
No
line.
.
V.
S!
There appears to be no
>:
of emission cross section on pr<
exist
's
may exist
p
h
several
in
However, similarities do
.
that a general relation-
the Lini
of
functional dependence
I
.
i
only
i
ine very
i
1889A
1
ised by an excita
la
thesis-
impur
1
I
hich is hypo-
I
to the nitrogen
er
ty
Improvement
:
i
i
;
technique may present a more
the expei imentaJ
in
-
'dependence.
Lon o
It
was pointed out earlier
three of the lines visible by photographic methods were of
that
too
intensity to be studied as
low
a
function of pressure.
This
study needs to be done.
A
;
th
being wr itten, steps are being taken to modify
pa]
i
the optical apparatus which may render this analysis feasible.
mecii
J 'hopper
nJ
..
,
Lf.
,
ier
is
.
to be employed in conjunction with a lock- in
I
he signal,
be alternating current.
darl
,
mitting analys
<'!!
Ls
intensity
chromete:
ilits whi
dude
•»
<
it
is
t
ipl ier
hoped, will result
very weak intensity.
should also permil
ul1
tube will
in
per-
This increased
the use of the regular moi
higher
wave
|th
resolution.
nave not been attempted in this paper,
I
;
,
from the photomul
This will greatly decrease the effect
and,
,
of lines of
vi
i
A
•
the pressure dependence.
required to obta
i
e
general picture
This experiment was carried out a1
ted proton energ
i
ll„
t
hi
enci gy
il
d pr ioi
of
the region of 1.6 MeV +
the beam prior
col] Lsiona]
to
n
<y
.
10 MeV.
rhis
to penetration of the aluminum foil
of the protons will have to be deter
Lute measurements.
25
-
9
Intensity in
t riry uni ts
^rbi
X
X X
X
X
X
X
X
to
Q
Q
#
Pressure in Torr
Q
a
POO
'
l
Figure
C
5.
3 or-
Intensity vs Pressure.
H
on Helium.
26
li.no
6678^ (2 P
5
-
00
3 D)
a
<
j
Tnt^ns
rD ry
'
"'"
*•
"
in
nit"
X
X
x x
x
x
x
x
X
IT
Prei.; are
Figure 6.
in Torr
Intensity vs Pressure. 7281A (2"p
H
+
,
•
on Helium.
27
-
3 S
p.
Intensity im
arbitrary units
10
3
§
Q
X
X
X
X
X
X
X
X
X
X
X
s,
;J^
X
Pressure in Torr
Figure 7.
300
200
100
400
3
Intensity vs Pressure. 38898 (2 S
H
on Helium.
28
500
•
3 P)
X
t
a
Int-ngi tv in
t vary uni
rbi
f*
x
y
x
Pr<» ;s
Q
Q
Q
r»
in ^orr
100
Figure
8.
5
Intensity vs Pressure. 5876& (2^P
H
on Helium.
29
-
no
3D).
.
Intensity in
arbi trprv uni
te
9
#
*
X
Pressure in Torr
2QQ
.inn
Figure 9.
3£>u
kQA
Intensity vs Pressure. 7065^ (2 3 P
H
on Hel ium
30
son
-
3 S).
X
Press ore /In tensi tr
fTorr/Arbi tr-T.r mita)
X
X
Press xtc in Torr
ion
Figure 10.
2QQ
3QQ
^2Q_
Pressure/Intensity vs Pressure. 6678X
1
(2 P
1
-
3
D).
31
H
on Helium
5Q£_
3
Pressure /intensity
(Terr/prbi tr?ry units)
X
Pressure in Torr
200
100
Figure 11.
^00
400
Pressure/Intensity vs Pressure. 7281A
X
(2 P
-
1
3 s).
32
H
on Helium,
500
"
r* 1
1
/t rbi
tra
r v
Ft-
(Torr
nten
jnits)
X
Press
Figure 12.
in Torr
100
?0Q
1Q0
ire
M_
^H
Pressure/Intensity vs Pressure. 7065A
3
(2 P
-
3
3
S)
.
33
H
+
on Helium.
X
Pressure /intensity
(Torr/Arbitrary units)
X
Pressure in T»rr
Figure 13.
300
?nn
JLiAL
UOQ
Pressure/Intensity vs Pressure. 5876$
3
(2 P
3D)
.
34
H
+
on Helium.
5
00
Pre?*? i)r»/lntenai ty
(
Tnrr/,".rl-ii
t
n rv
init?)
X
X
X
x
x x
x x
X
X
I
x
X
X
X
X
Prestare in Torr
8<
100
Figure l4.
ZQD
~iQo
iiOD
Pressure/Intensity vs Pressure. 3889A
3
(2 S
-
3 P).
35
H
+
on Helium.
s on
Figure 15.
Drift tube, collision chamber and control manifold,
36
Figure 16.
Optical equipment in position
37
Figure 17-
Control console and measuring devices
38
.
BIBLIOGRAPHY
1.
Allen, C.W. Astr ophysi ca 1 Quant it ies
Press, 1955.
2.
F.J. "Experimental Studies of Excitation in
De Heer
Collisions between Atomic and Ion Systems", Advances in
Atom c and Molecular Phys ics
D.R. Bater and I. Estermann,
editor. Vol. 2 New York: Academic Press, 1966, pp. 328-384.
.
London: The Athlone
,
i
.
i< I,
A. 11., and D.W.O. Heddle. "Excitation processes in
helium", Proceedings of the Royal Society 258: 124-145, I960.
Gabi
,
4.
Hasted, J.B. Phys
and Co.
19^4.
ir s
of A t om i c Coll is ions
.
London: Butterworth
,
5.
'>.
lei /berg, G. Mol ecular
Spectra and Molecul ar Str uctur e.
2nd edil ion. New York: D. Van Nor strand Company, Inc., 1950.
I
The I dent if ica t ion of
Pearse, R.W.B. and A.G. Gaydon.
Mol ocular Spectra
Jrd edition. New York: John Wiley and
Son Im
.
.
7.
'
,
I
and P. Thomas.
"Excitation Processes in
Sternberg, Z.
Induced by Impact of Deuterons and Protons", The
Physical Review 124: 8l()-8l3, 1961
,
He] ium
.
,
8.
Thomas, E.W. "Cross Sections for the Formation of Excited
States in a Helium Target by the Impact of 0.15- to 1.0Comparison with Theory",
II.
MeV Protons and Deuterons.
164: 151-155, 1967.
The Physical Review
,
9.
"Formation of Excited States
Thomas, E.W., and G.D. Bent.
of 0.15- to 1.0- MeV
by
the
Impact
Target
in a Helium
Experimental",
The Phys ical Review
Deuterons,
I.
Protons and
164: 143-150, 1967.
,
„
Atomic Transition
Wiese, W.L., M.W. Smith, and B.M. Glennon.
Probabilities Hydr ogen Thr ough Neon. National Bureau of
Standards, Department of Commerce, Washington: Government
Printing Office, 1966
11.
Tables of
Zaidel, A.N., V.K. Prokof'ev, and S.M. Raiskii.
New York: The Macmillan Company, I961.
Specti urn L ines
.
39
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3.
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Department of the Army
Washington, D.C. 20310
1
4.
Prof. E.A. Milne
Department of Physics
Naval Postgraduate School
Monterey, California 93940
2
5.
Prof. R.L. Kelly
Department of Physics
Naval Postgraduate School
Monterey, California 93940
1
6.
Maj. B.J. Tullington, Jx
107 E. Virginia Avenue
Hampton, Virginia 23363
7.
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REPOR1 SECURITY CLASSIFICATION
La
i
i
The Excitation of Helium by High Energy Proton Bombardment at Various
Pi
ssur es
i
DESC Rll
4
'/
'
i
;/'
ol
" port and,
ini hi
Thesis, MS, June 1968
ad
g
First
1
name, middle
initial,
laitl
Tullington, Bernard J., Jr., MAJ, USA
-
1
1
June 196X
ORIGINATOR'S REPOI
9a.
N/A
h.
1
IBER(S)
N/A
NO
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11
JlL
ONTRACT OB GRANT NO
'her
I
•-,
1
I
1
I
I
.
'
I
.
I
.1
T
I
I
5UPPLI M
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N
T
A
R
Y
nnlvflHI
ABSTRAl
bet
that
way 6e assigned
erf
thf-
N<
Naval Postgraduate School
N/A
13
•
O N STAT'
to
tons aav-~trp~ rmrte
I
i
T
The intensities of several helium spectral lines are analyzed for their dependence on pressure.
Neutral helium was bombarded by protons, accelerated in
a
Van de Graaff generator to energies of 1.6 MeV before they passed through an
aluminum foil window into the collision chamber.
Eight helium emission lines
and one nitrogen line (impurity) were detected by photographic analysis of the
collision spectrum at various pressures.
Relative intensities of five of the
helium emission lines were measured with photoelectric apparatus at pressures
from 10 "^
550 Torr
-
.
Lines of 6678$, 728l^, 7065R and 5876^ show a similiar,
but not exact, functional dependence on pressure.
have
a
quite different pressure dependence thay may possibly be due to the
nitrogen impurity.
DD
The 3889X line appears to
73
,?„?., 14
S/N 0101 -807-681
1
Suggested experimental improvements are discussed.
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Emission cross section
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Emission intensity
Excitation cross section
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