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73-lL*
PROGRESS REPORT FOR
JUNE, JULY 8i AUGUST, 1964
COORDINATED SCIENCE LABORATORY
URBANA I ILLINOIS
UNIVERSITY OF ILLINOIS
T h e r e s e a r c h r e p o r t e d i n t h i s d o c u m e n t w a s m a d e p o s s i b l e by s u p p o r t e x t e n d e d
to
t h e U n i v e r s i t y of Illinois I C o o r d i n a t e d S c i e n c e L a b o r a t o r y , u n d e r t h e Joint S e r v i c e s E l e c t r o n i c s Program by t h e D e p a r t m e n t of t h e Army, D e p a r t m e n tof
t h e N a v y ( O f f i c e of N a v a l R e s e a r c h ) , and t h e D e p a r t m e n t of t h e Air F o r c e ( O f f i c e of S c i e n t i f i c R e s e a r c h ) , a n d b y t h e Advanced R e s e a r c h P r o j e c t s Agency u n d e r D e p a r t m e n t of t h e Army c o n t r a c tDA- 2 8- 0 4 3 -AMC- 00 07 3 (E)
t h e N a t i o n a l A e r o n a u t i c s a n d S p a c e Administration u n d e r G r a n t s
NsG 376 N s G 4 4 3 N s G 504
a n d D e p a r t m e n t of t h e Air F o r c e ( O f f i c e of S c i e n t i f i c
R e
s e a r c h ) c o n t r a c tAF 4 9 ( 6 3 8 )
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1383November 9, 1964
ii COORDINATED SCIENCE LABORATORY
SUMMARY OF
PROGRESS REPORT FOR
JUNE,JULY, AUGUST,
1 9 6 41. Aerospace Group
Three rockets employing closed loop instrumentation for radio propagation measurements in the D region of the ionosphere were fired before, during, and after sunrise on July 15,
1 9 6 4 .Reduced data from the April 16 shot is presented.
2 .
Surface and Atomic Physics
Results
o ftests
ofan ultrahigh vacuum, rotary-motion, feedthrough are reported. An experiment to study the elastic and inelastic scattering of electrons at solid surfaces is described. A study
ofthe cross-section for scattering and ionization
o fbarium atoms by low energy electrons is reported.
on experiments to study the adsorption-desorption kinetics of gases at solid surfaces, the angular distribution
o fsecondary electrons, and Auger electron ejection is given.
A
summary of the progress
3 .
Computer Application Group
Continuing developments on an experimental time-sharing
system are reported. Improvements and additions to the SMP-CSX-1
Bubble Chamber Data Processing work are described,
iii
4 . Sys
tems
An important problem in the computer analysis of networks, namely the generation of trees without duplication, has been solved.
The necessary and sufficient conditions for the realizability of a given state diagram as a quasi-linear sequential machine have been
obtained. The necessary and sufficient conditions for the realizability of a given matrix as the A matrix (state matrix) of an RLC half-degenerate network have been found.
cedure into the right half plane is complete. Further progress is reported on the problems of the path matrix of a contact network, lossy communication networks, and self-diagnosing computers. New results in coding theory relate to the transmission rate in a communication channel.
Several studies
ofnonlinear oscillating systems have been completed and are reported.
studies of stability, system optimization, and rendezvous strategies.
The extension of the Dasher synthesis pro-
In the area of control, progress is reported in
5. PLATO
Progress on the construction and circuitry of the twenty
student station teaching system indicates that at least ten student
stations will be operable in November. The compiler, CAT0 (Compiler
for Automatic Teaching Operation), has been completed. The resident
program for CAT0 is now completely revised to allow for more efficient
use of the PLATO 111 equipment, and compatibility with CATO-compiled
programs. The inquiry training lesson, REPLAB, has been used further,
this time by a demonstration class in a teacher's summer workshop on
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i n q u i r y t r a i n i n g t e c h n i q u e s . A s h o r t experiment i n t e a c h i n g s m a l l c h i l d r e n t h e l e t t e r s of t h e a l p h a b e t h a s s u g g e s t e d some o f t h e problems i n v o l v e d i n u s i n g PLAT0 w i t h v e r y young c h i l d r e n .
under development i n c l u d e s a t e x t book t e s t e r . The f e a s i b i l i t y o f e x t e r n a l l y c o n t r o l l e d d i s c h a r g e s h a s been s u c c e s s f u l l y d e m o n s t r a t e d i n c o n n e c t i o n w i t h t h e plasma d i s c h a r g e d i s p l a y t u b e r e s e a r c h p r o j e c t .
New l e s s o n m a t e r i a l
6 . Vacuum I n s t r u m e n t a t i o n
Work on u l t r a h i g h vacuum mass s p e c t r o m e t e r s t u d i e s i s r e p o r t e d . M o d i f i c a t i o n s t o t h e p h o t o c u r r e n t s u p p r e s s o r gauge show a c o n s i d e r a b l e
improvement i n performance i s p o s s i b l e . Some methods o f r e p a i r i n g poor q u a l i t y o r damaged s t o r a g e tubes a r e d i s c u s s e d . Impact i o n i z a t i o n
c o e f f i c i e n t s f o r CO on molybdenum and
O2
and CO on p l a t i n u m a r e r e p o r t e d .7 . Plasma P h y s i c s
An a l g e b r a i c t h e o r y o f shock s t r u c t u r e h a s been completed.
T h e r e s u l t s o f t h i s t h e o r y and o f r e c e n t Monte C a r l o c a l c u l a t i o n s have l e d t o t h e p r e l i m i n a r y d e s i g n o f a new n u m e r i c a l i n t e g r a t i o n scheme f o r t h e Boltzmann e q u a t i o n . T h e o r e t i c a l work on o s c i l l a t i o n s i n non- uniform plasmas was s t a r t e d . One p a r t i c u l a r model i s d i s c u s s e d i n
some d e t a i l . The e i g e n v a l u e s o f o s c i l l a t i o n a r e c a l c u l a t e d e x p l i c i t l y .
8. High Maqnetic F i e l d S u p e r c o n d u c t o r s
P r o g r e s s i s r e p o r t e d i n t h e f o l l o w i n g a r e a s : (1) P r e p a r a t i o n o f s i n g l e c r y s t a l l i n e NbgSn; ( 2 ) S t u d i e s o f c u r r e n t peaks i n t h e c u r r e n t - v o l t a g e c h a r a c t e r i s t i c s of s u p e r c o n d u c t i n g t u n n e l i n g j u n c t i o n s r e l a t e d
V
t o t h e AC Josephson e f f e c t ; (3) Superconducting p r o p e r t i e s o f t h a l l i u m - antimony a l l o y s ; and ( 4 ) Development o f a v e r y s e n s i t i v e low impedance v o l t a g e d e t e c t o r ,
9 . High V o l t a g e Breakdown
The s i g n i f i c a n c e of c r i t i c a f i e l d v a l u e s f o r breakdown i s d i s c u s s e d . O b s e r v a t i o n s o f emission p o i n t s on b r o a d e l e c t r o d e s , t h e e f f e c t o f g a s on prebreakdown c u r r e n t s , t h e u s e o f g o l d e l e c t r o d e s , and f u r t h e r o b s e r v a t i o n s o f f i e l d - e m i s s i o n f l i c k e r a r e r e p o r t e d .
10. Thin Films
Photoconductive measurements have been made on t i n o x i d e f i l m s i n t h e c o n t i n u i n g e f f o r t t o l e a r n more a b o u t t h e e l e c t r o n i c
s t r u c t u r e o f t h i s m a t e r i a l . Using h e a t e d s u b s t r a t e s , f i l m s of vanadium and niobium have been made which have normal s u p e r c o n d u c t i n g p r o p e r t i e s . T h i s i s an i m p o r t a n t improvement o v e r e a r l i e r r e s u l t s .
were h e a t e d u s i n g a n evaporated t i t a n i u m f i l m on t h e r e v e r s e s i d e on t h e s u b s t r a t e a s a r e s i s t i v e h e a t i n g element. E l e c t r o n d i f f r a c t i o n and e l e c t r o n microscope photographs have been made o f t h e s t r u c t u r e o f some t i n f i l m s grown on cleaved NaCl s u b s t r a t e s . P r e l i m i n a r y a t t e m p t s have been made t o d e p o s i t by e v a p o r a t i o n l u m i n e s c e n t s c r e e n s .
The s u b s t r a t e s
11. Computer O p e r a t i o n s
O p e r a t i n g s t a t i s t i c s , equipment m o d i f i c a t i o n s , and systems programming a r e r e p o r t e d .
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COORDINATED SCIENCE LABOMTORY
Personnel
F a c u l t y , Research A s s o c i a t e s , and Research E n g i n e e r s A l p e r t , D . , D i r e c t o r
Anderson, R . Ash, R . B.
B a r n a r d , H. M . B i t z e r
,
Donald Bzhmer, H.Brown, R . M.
Chen, W . K . Cooper, D. H.
Cruz, J , B.
Dodd, G , E l l i o t t , B.
Fenves, S , F r a n z , Frank F r a u e n f e l d e r , H.
G e n t r y , W
.
Gooch, J . H i c k s , B. L . Kirkwood, B.
Assoc. D i r e c t o r
Aggarwal, J . K . B a r g e r , A . R . B a t c h e r , K . Berns t e i n , R.
Blomme, R .
Chang, H e r b e r t Y.
Chen, W . K . Cooper, T.
C r a f o r d , M.
Crowder
,
James Cumming s,
James D e r v i s o g l u , A.Agashe, S . C a r r , W.
Knoebel, H.
Kopplin, J . 0.
Krone, H . V . Kypta, L . Lee, D . A .
L e i c h n e r
,
E . J.
L i c h t e n b e r g e r , W , W . (on l e a v e )
Liischer, E . (on l e a v e ) Lyman, E l i s a b e t h
Lyman, E r n e s t Mayeda
,
W . M u e l l e r , T.Peacock, R . N.
P e r k i n s , W.
Ponzo, P . P r o p s t , F.
P r o t h e , W . C . R a e t h e r , M.
A s s t . t o D i r e c t o r
Research A s s i s t a n t s DeWan; E .
Gieseking
,
D . Hosken, R . Hummel, F . J a c o b s , J . T.J e n k s , R i c h a r d L i e , T .
Manning, E . McKellar, A.
Mendel, C . Morgan
,
L e z l i e Murata, T.Fellows P a u l , A . Rain, D.
Resh
,
J .R e t h e r f o r d , R . C , R o h r e r , R ,
S a t t e r t h w a i t e , C. B.
Schuemann, W . C . Seshu, Sundaram S i m o n e l l i , L , S k a p e r d a s , D . S l o t t o w , H. G . S o b r a l , M , S t e i n r i s s e r , F.
S t i f l e
,
J , Tomaschke, H. E . Trogdon, R .Van Valkenburg, M. E . Voth, B ,
Wax, Nelson
Assoc. D i r e c t o r
Onaga, K . P i p e r , Thomas
S e c r e s t , M.
Smith, M a r g a r e t Snyder, D , P.
S o b r a l , M . Tahim, G . T i b b e t s , G . Toepke, I . Werner, R . W i l l s o n , R . H.
Z e l a c , R .
S a i n , M . Win, S .
Secretary Storekeepers Gschwendtner,
J.Drews, C. E.
Rudicil , J. Lofton, C.
Accountant Klein, N.
Typists and Stenos Electronic Technicians Barnard, M.
Christy, L.
Harris, M, Long , W.
Lucas, B.
McDonald, R.
Vancleave, C.
Instrument Makers Beaulin, W. E.
Merritt, K. E.
Zackery, R. L.
Glassblower Lawrence , W.
Phys. Sci. Staff Asst.
Thrasher, W.
Alper, G.
Alpert, A.
Arnold, C.
Ar tman , J .
Bleha , W.
Chilton, S.
Edelheit, L.
Etienne,
L .Ewen, D.
Frampton, G.
Casale, T.
Coad, D. E.
Cooper, G.
Crawford, G.
Deschene, D.
R .Holy, F.
0.Jordan, H.
Knoke, J. G , Merrifield, F.
Roberts, G.
Schmidt , W.
Streff, L. W.
Turpin,
F.G.
Student Assistants Gibson, N.
Gobberdiel, J.
Hanson, A.
Johnson, M.
Jones, A.
Karr, G.
Klingbiel, R.
Metze, V.
Nagel, D, Nash, R.
vi
iAccounting Clerk Hanoka, Nila Potter, R. E, Photographer Fillman, W.
Draftsmen Conway, E.
MacFarlane, R. F.
Tewes, A. F ,
Laboratory Mechanics Bouck, G.
Burr, J. G.
Electronics Engr. Asst.
Carter, E. N.
Gardner,
0.E.
Hedges, L.
Neff, E. H.
Vassos, N.
Res. Lab. Shop Supr.
Bandy, L.
Riddle, G.
Ries, R.
Robinett, D.
Samson, C.
Sandorfi, G.
Singer, S.
Ulbrich, N.
Walker , M , Whitney, R.
Klein , W.
viii PUBLICATIONS AND REPORTS
1.
Journal Articles Published or Accepted
F. A. Franz and E, Llischer, "Spin Relaxation Pumped Cesium," Phys. Rev. 135, A582 (1964).
2. Meeting Papers
f Opti
Peter Braunfeld, "Computer-Based Teaching Systems as Aids to Human Reasoning," Symposium on Computer Augmentation, July 17,
1964, Washington, D. C.
J. B. Cruz, Jr. and W. R, Perkins, "The Role of Sensitivity in the Design of Multivariable Linear Systems," National Electronics Conference, October, 1964, Chicago, Illinois.
C. B. Satterthwaite, M. G. Craford, R. N. Peacock, and R. P. Ries,
"DCPair Tunneling between
TwoSuperconductors at Finite Voltages," Ninth International Conference on Low Temperature Physics, August 31-September 4, 1964, Columbus, Ohio.
3 .
Technical Reports
R-218 Control of Co-operative Systems: The Rendezvous Problem; D. Gieseking.
R-219 Memory Effects in the Current-Voltage Characteris- tics of Thin Film Sandwiches; G. Riddle,
R-215 Role of the Generalized Lipschitz Condition in Finite-Time Stability and in the Derivation of
the Maximum Principle;
S .D. Agashe.
R-227 The Sensitivity of General Multivariable Feedback Systems; J. B. Cruz, Jr. and W. R. Perkins.
R-232 Anomalous Current Peaks in the I-V Characteristic for Tunneling between
TwoSuperconductors;
M. G. Craford, R. N. Peacock, R. P. Ries, and
C. B. Satterthwaite.
ix TABLE OF CONTENTS
Page
1 . Aerospace Group . . .
12 . Surface and Atomic Physics . . . 7
2.1 Introduction . . . 7
2.2 Rotary-Motion Feedthrough . . . 8
2.3 Electron Scattering
atSolid Surfaces . . . 8
2.3.1 Introduction . . . 8
2.3.2 Experimental Apparatus . . . 12
2.4 Total Cross-Sections for Scattering and for Ionization of Barium Atoms by Low Energy Electrons . . . 14
3 . Computer Research Applications . . . 18
3.1 Introduction . . . 18
3.2 Logical Design . . . 18
3.3 The DIOG Experimental Time-sharing System . . .
1 93.4
SMP Bubble Chamber Data Processing. . . 20
4 . Systems . . . 21
4.1 Generation
ofTrees without Duplication . . . 21
4.2 Quasi-Linear Sequential Machines . . . 22
4.3 Self.Diagnosis . . . 22
4.4 Synthesis of Sequential Machines . . . 23
4.5 Directed Graph Studies . . . 23
4.6 Lossy Communication Nets . . . 24
4.7 A-Matrix Synthesis . . . 24
4.8 Dasher Synthesis . . . 25
4.9 Distributed Netowrk Synthesis . . . 26
4.19 Coding Theory . . . 26
4.U Nonlinear Oscillating Systems . . . 27
4.11.1 4.11.2 P .
J. Ponzo and N . Wax. "On Certain Relaxation J. K . Aggarwal. "A Study of Nonlinear Second Order Systems. .. R.223 . . . 27
Oscillations: Confining Regions. .. R-228 . . . . 28
X
CONTENTS (Continued)
Page
4.12 4.13 4.14 4.15 4.16 4.u 4.18 4.19 4
.a
4.11.3 P
.
J.
Ponzo and N.
Wax. "On C e r t a i n R e l a x a t i o n 4.11.4 P.
J.
Ponzo and N.
Wax. "On t h e P e r i o d i cO s c i l l a t i o n s : Asymptotic S o l u t i o n s . " R-229
. .
2930 S o l u t i o n o f t h e van d e r P o l Equation.
. . .
Finite-Time S t a b i l i t y and Maximum P r i n c i p l e f o r Systems S a t i s f y i n g a G e n e r a l i z e d L i p s c h i t z C o n d i t i o n Linear T i m e Lag Systems. . .
S t o c h a s t i c Optimal C o n t r o l. . .
3 1 Optimum Time Lag Systems. . .
32A F i n i t e Z-Transform P a i r
. . .
3 4 Optimal Rendezvous S t r a t e g i e s. . .
3 4 Graph Theory. . .
35. . .
303 1 Optimum C o n t r o l w i t h a P r e s c r i b e d S t r u c t u r e .
. . .
33P u l s e - W i d t h M o d u l a t i o n Systems
. . .
3 4 5.
PLAT0. . .
375 . 1 I n t r o d u c t i o n
. . .
375.2 PLATO 111 System Equipment (PLATO Hardware)
. . .
375 . 3 PLATO I11 Computer Programming (PLATO S o f t w a r e )
. . .
385.3.1 The R e s i d e n t Program f o r CATO (CATORES)
. . .
385.3.3 The CATO (Compiler f o r Automatic O p e r a t i o n s ) 5.3.2 DOPEREA
. . .
39System
. . .
4 0 5 . 4 Plasma Discharge Display Tube Research. . .
4 0 5.5 PLATO Learning and Teaching Research. . .
415.5.1 I n q u i r y T r a i n i n g (REPLAB)
. . .
415.5.2 Teaching A B C ' s
. . .
425.5.3 TEXT TESTER
. . .
425 . 5 . 4 PROOF
. . .
436
.
Vacuum I n s t r u m e n t a t i o n. . .
446 . 1 Mass Spectrometer S t u d i e s
. . .
446.2 P h o t o c u r r e n t Suppressor Gauge
. . .
456.3 R e p a i r i n g o f Damaged o r Unusable S t o r a g e Tubes
. . .
496 . 4 Impact I o n i z a t i o n S t u d i e s
. . .
5 0xi CONTENTS (Continued)
Page
7 . Plasma Physics . . . 52
7.1 The Boltzmann Equation for a Shock Wave . . . 52
7.2 Oscillations in Non-Uniform Plasmas . . . 54
7.3 Bibliography . . . 59
8 . High Magnetic Field Superconductors . . . 63
8.1 Introduction . . . 63
8.3 Superconducting Tunneling . . . 64
8.4 Micro-micro Voltmeter . . . 72
8.2 Superconductivity in Thallium-Antimony Alloys . . . 63
8.5 Crystallization of Nb 3 Sn . . . 73
9 . High Voltage Breakdown . . . 78
9.1 Critical Field for Tungsten Electrodes . . . 78
9 . 3
Effect of Gas on the Predischarge Current . . . 81
9.2 Multiple Points on Broad Electrodes . . . 79
9.4 Predischarge Current and Voltage Breakdown between Gold Electrodes . . . 81
9.5 Flicker and Rectangular Pulses . . . 82
10
. Thin Films . . . 84
1Q.1 Tin Oxide Films . . . 84
10.2 Hard Superconducting Films . . . 84
10.3 Epitaxial Films . . . 85
10.4 Luminescent Films . . . 86
11
. Computer Operations . . . 88
11.1 Introduction . . . 88
11.2 CSX-1 Computer . . . 88
11.2.1 Operations . . . 88
11.2.2 Modifications . . . 88
11.3 CDC 1604 Computer . . . 89
11.3.1 Operations . . . 89
11.3.2 Systems Programming . . . 89
H. Knoebel
D. Skaperdas
B. Kirkwood
1
1. AEROSPACE GROUP
H. Krone J . Gooch G. Karr
W . P r o t h e R . Anderson
On J u l y 15, 1964, the Coordinated S c i e n c e L a b o r a t o r y f i r e d t h r e e r o c k e t s o f t h e Nike-Apache t y p e i n a s e r i e s o f e x p e r i m e n t s p r o b i n g t h e i o n o s p h e r e . T h i s w a s conducted under a s y n o p t i c I n t e r - n a t i o n a l Year o f t h e Q u i e t Sun
(IQSY)
program which i s d i r e c t e d by D r . Sidney Bowhill. The experiments f o r which CSL was r e s p o n s i b l e were o f a s i m i l a r n a t u r e a s t h e one conducted A p r i l 1 6 , 1964, and r e p o r t e d i n t h e CSL P r o g r e s s Report f o r March, A p r i l , and May, 1964.The purpose o f t h e s e p r o p a g a t i o n e x p e r i m e n t s i s t o measure t h e e l e c - t r o n c o l l i s i o n f r e q u e n c y p r o f i l e o f t h e D r e g i o n f o r t h r e e d i f f e r e n t c o n d i t i o n s ; i . e . , b e f o r e , d u r i n g , and a f t e r s u n r i s e .
All
t h r e e p r o p a g a t i o n e x p e r i m e n t s were s u c c e s s f u l l y conducted i n t h e c l o s e d loop mode, i n which a servomechanism c o n t r o l s t h e e x t r a - o r d i n a r y wave t r a n s m i t t e d power, a s e x p l a i n e d i n t h e p r e v i o u s p r o g r e s s r e p o r t . I n a d d i t i o n t o a l l the s i g n a l s which were t e l e m e t e r e d from t h e r o c k e t t o t h e t e l e m e t r y s t a t i o n s i n t h e A p r i l 1 6 e x p e r i m e n t , t h er e c e i v e r a u t o m a t i c g a i n c o n t r o l v o l t a g e was i n c l u d e d i n t h e t h r e e J u l y 15 e x p e r i m e n t s . The a v a i l a b i l i t y o f t h i s i n f o r m a t i o n , t o g e t h e r w i t h r o c k e t a n t e n n a and receiver c a l i b r a t i o n d a t a , a l l o w s a d e t e r m i n a -
t i o n o f o r d i n a r y wave e l e c t r i c f i e l d i n t e n s i t y v e r s u s h e i g h t t o be made. It a l s o a l l o w s c o r r e c t i o n s o f t h e d i f f e r e n t i a l a b s o r p t i o n pro-
f i l e f o r n o n l i n e a r r e c e i v e r c h a r a c t e r i s t i c s .
2
S i n c e t h e s u n ' s u l t r a v i o l e t l i g h t i s t h e main i o n i z i n g a g e n t f o r t h e D r e g i o n , c o n d u c t i n g a s e r i e s of r o c k e t p r o b e s a t p r e c i s e l y known i n t e r v a l s b e f o r e and a f t e r s u n r i s e p r o v i d e s f o r t h e measurement o f t h e p h o t o i o n i z a t i o n buildup due t o t h e sun. Hence, one s h o u l d o b s e r v e v e r y l i t t l e d i f f e r e n t i a l a b s o r p t i o n and Faraday r o t a t i o n b e f o r e s u n r i s e a s compared w i t h a f t e r s u n r i s e . The a c t u a l d i f f e r e n t i a l a b s o r p t i o n and Faraday r o t a t i o n d a t a , v e r s u s t i m e a f t e r l a u n c h , f o r r o c k e t f i r i n g 14.144, d u r i n g which t h e e a r t h ' s shadow w a s up a t a b o u t 330 Km, and f o r r o c k e t f i r i n g 14.146, a t which t i m e t h e r e was no e a r t h shadow a t t h e l a u n c h a r e a , a r e shown i n F i g u r e s 1.1 and 1.2, r e s p e c t i v e l y . The d i f - f e r e n t i a l a b s o r p t i o n d a t a f o r f l i g h t 14.146 does show a h i g h e r t r e n d t h a n t h a t f o r f l i g h t 14.144, b u t n o t v e r y c l e a r l y . The r e a s o n f o r t h e l a r g e f l u c t u a t i o n s i s n o t p r e s e n t l y known. F l u c t u a t i o n s o f t h i s magni- t u d e were n o t o b s e r v e d i n t h e d i f f e r e n t i a l a b s o r p t i o n d a t a f o r f l i g h t 14.143 f i r e d A p r i l 1 6 , 1964. The Faraday r o t a t i o n d a t a , on t h e o t h e r hand, shows c l e a r l y t h e expected d i s s i m i l a r i t i e s between t h e two f l i g h t s . I n f l i g h t 14.144, t h e t o t a l Faraday r o t a t i o n was a p p r o x i m a t e l y t h r e e c y c l e s , whereas i n f l i g h t 14.146 i t was a b o u t 13-112 c y c l e s .
f a c t i s t h a t t h e h e i g h t a t which t h e e x t r a o r d i n a r y wave was r e f l e c t e d i n f l i g h t 14.143, a s i n d i c a t e d by t h e a b r u p t r i s e i n t h e c o r r e s p o n d i n g d i f f e r e n t i a l a b s o r p t i o n and Faraday r o t a t i o n c u r v e s (82 seconds a f t e r l a u n c h , which c o r r e s p o n d s t o an a l t i t u d e o f a b o u t 50 m i l e s ) a p p e a r s lower t h a n t h a t f o r f l i g h t 14.146, whereas t h e o p p o s i t e s h o u l d p r e v a i l .
A p u z z l i n g
D e t a i l e d d a t a a n a l y s i s i s b e i n g c o n t i n u e d on a l l f o u r r o c k e t f i r i n g s i n o r d e r t o e x t r a c t t h e maximum d a t a . By means o f
14.146 14.144
-
. . . .
3
Time after launch (seconds)
Figure 1.1. Absorption Data.
4
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14.143 April 16,1964
' I
Magnetic aspect sensorenvelope va r io t ion
20 30 40 50 60 70
Time after launch ( seconds 1 Figure 1 . 2 . Faraday Rotation Data.
5
s t a t i s t i c a l a n a l y s i s , Faraday r o t a t i o n d a t a i s b e i n g e x t r a c t e d w i t h a r e s o l u t i o n of a b o u t one degree. I n t h i s way, a s l i g h t d e c r e a s e w i t h h e i g h t i n Faraday r o t a t i o n b e f o r e i t s l a r g e r monotonic i n c r e a s e may be concluded from t h e d a t a shown i n F i g u r e 1 . 3 f o r f l i g h t 14.143. This d a t a h a s been c o r r e c t e d f o r phase s h i f t s which were i n t r o d u c e d by t h e e l e c t r o n i c c i r c u i t r y used t o e x t r a c t t h e d a t a from t h e t e l e m e t r y t a p e s . Another c i r c u i t i s b e i n g d e s i g n e d which should e l i m i n a t e t h e s e phase
s h i f t s . I n F i g u r e 1 . 3 t h e r e i s a v e r y s t r o n g c o r r e l a t i o n w i t h t h e r o c k e t ' s p r e c e s s i o n a b o u t i t s t r a j e c t o r y p a t h , a s shown by t h e s k e t c h o f m a g n e t i c s e n s o r e n v e l o p e v a r i a t i o n v e r s u s t i m e .
A second van i n s t a l l a t i o n c o n t a i n i n g a l l t h e ground-based equipment e x c e p t t h e a n t e n n a i s b e i n g completed f o r u s e aboard a n a i r c r a f t c a r r i e r . One o f t h e f i r i n g s aboard t h e c a r r i e r may t a k e p l a c e a t t h e e a r t h ' s magnetic e q u a t o r , a t which t h e r o c k e t t r a j e c t o r y would be t r a n s v e r s e t o t h e e a r t h ' s magnetic f i e l d . For t h i s t r a n s v e r s e
c a s e a s e t o f m u t u a l l y p e r p e n d i c u l a r l i n e a r l y p o l a r i z e d waves, i n s t e a d o f o p p o s i t e l y c i r c u l a r l y p o l a r i z e d waves, would e x h i b i t d i f f e r e n t i n d i c e s o f r e f r a c t i o n w i t h the r e s u l t a n t d i f f e r e n t i a l a b s o r p t i o n and Faraday r o t a t i o n . The u s e of m u t u a l l y p e r p e n d i c u l a r l i n e a r l y p o l a r i z e d t r a n s m i t t e d waves p l a c e s a g r e a t e r burden on t h e r o c k e t r e c e i v i n g
a n t e n n a , which must be c i r c u l a r l y p o l a r i z e d i n o r d e r t o r e c e i v e b o t h l i n e a r l y p o l a r i z e d waves r e g a r d l e s s o f azimuth. C i r c u i t s t o do t h i s a r e now being t e s t e d .
D. Skaperdas
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Time after launch (seconds)
F i g u r e 1 . 3 . Faraday R o t a t i o n .
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Surf ace:
F. P r o p s t R. R e t h e r f o r d F. S t e i n r i s s e r L. S i m o n e l l i T. Cooper G . T i b b e t t s T. P i p e r
7
2 . SURFACE
AND
ATOMIC PHYSICSAtomic:
H. F r a u e n f e l d e r F. Franz
2 . 1 I n t r o du c t i o n
I n t h e p r e v i o u s p r o g r e s s r e p o r t , a n experiment t o s t u d y t h e a n g u l a r d i s t r i b u t i o n o f e l e c t r o n s e j e c t e d by i o n s and by e l e c t r o n s s t r i k i n g a s o l i d s u r f a c e and an experiment t o s t u d y t h e a d s o r p t i o n - d e s o r p t i o n k i n e t i c s of g a s e s a t s o l i d s u r f a c e s were d e s c r i b e d . The
d e s i g n o f t h e s e two experiments i s e s s e n t i a l l y complete and t h e a p p a r a t u s i s b e i n g c o n s t r u c t e d . It i s p o s s i b l e t h a t b o t h o f t h e s e systems w i l l be assembled d u r i n g t h e n e x t q u a r t e r .
An i n s t r u m e n t designed t o s t u d y t h e s c a t t e r i n g o f e l e c t r o n s from s o l i d s u r f a c e s h a s been d e s i g n e d . It i s f e l t t h a t t h i s t e c h n i q u e i s p o t e n t i a l l y v e r y powerful i n t h a t a l a r g e number o f p r o c e s s e s c a n p o s s i b l y be s t u d i e d by i t .
s t u d y i o n e m i s s i o n by e l e c t r o n impact u s i n g t h i s system.
r e s o l u t i o n (0.1 V) i s p o s s i b l e , t h e s e e x p e r i m e n t s may prove t o g i v e sub- s t a n t i a l d a t a amenable t o t h e o r e t i c a l a n a l y s i s - - a s o r e l y needed commodity i n t h e a r e a o f s u r f a c e s c i e n c e . This system i s d e s c r i b e d i n g r e a t e r d e t a i l below.
I n a d d i t i o n , i t may a l s o be p o s s i b l e t o S i n c e h i g h
The a p p a r a t u s used i n t h e s t u d y o f Auger e l e c t r o n s ( t h e s e e x p e r i m e n t s and r e s u l t s have been p r e s e n t e d i n s e v e r a l p r e v i o u s p r o g r e s s
8
r e p o r t s ) h a s been m o d i f i e d , and work i n t h i s a r e a i s c o n t i n u i n g . I n a d d i t i o n , t h e s c a t t e r i n g o f ions from s o l i d s u r f a c e s w i l l be i n v e s t i - g a t e d i n t h i s system.
2.2 Rotary-Mo t i o n Feedthrough
The u l t r a h i g h vacuum, r o t a r y - m o t i o n f e e d t h r o u g h d e s c r i b e d i n 1 t h e p r e v i o u s p r o g r e s s r e p o r t h a s been c o n s t r u c t e d . The o u t p u t s h a f t was l u b r i c a t e d w i t h d r y MoS2 powder.2
was o b t a i n e d u s i n g a s m a l l o i l pumped system.
were w a t e r c o o l e d d u r i n g bakeout. P r e s s u r e i n c r e m e n t s from 2x10 T o r r t o 5 ~ 1 0 - ~ T o r r were observed c o r r e s p o n d i n g t o a n g u l a r speeds from 1 RPM t o about 50 RPM.
A vacuum o f a b o u t 5x10 -10 T o r r The e x t e r i o r b e a r i n g s
-10
It i s e x p e c t e d t h a t t h e vacuum can be improved by removing t h e e x t e r i o r b e a r i n g s and using a clamp f o r bakeout i n s t e a d of w a t e r , c o o l i n g . This w i l l a l l o w the b e l l o w s and o u t p u t b e a r i n g s t o be baked a t a h i g h e r t e m p e r a t u r e .
T. Cooper 2.3 E l e c t r o n S c a t t e r i n g a t S o l i d S u r f a c e s
2.3.1 I n t r o d u c t i o n . I n d i r e c t e v i d e n c e t h a t e l e c t r o n s l o s e e n e r g y i n d i s c r e t e amounts i n i n t e r a c t i n g w i t h t h e s u r f a c e r e g i o n o f s o l i d s i s g i v e n by s t u d i e s of t h e Auger e l e c t r o n energy d i s t r i b u t i o n ( c a u s e d by slow He i o n s i n c i d e n t on s o l i d s u r f a c e ) f o r s u r f a c e s w i t h 3
'Progress Report f o r March, A p r i l , May, 1964. S e c t i o n 2.2, page 26: Angular D i s t r i b u t i o n o f Auger E l e c t r o n s .
2The MoS2 powder was o b t a i n e d from t h e Moly-Kote Company.
3F. M. P r o p s t and E. Liischer, Phys. Rev.
132,
1037 (1963).9
v a r y i n g a d s o r b a t e coverage. S t u d i e s of t h e p h o t o - e l e c t r i c e l e c t r o n energy d i s t r i b u t i o n emerging from s u r f a c e s o f v a r y i n g a d s o r b a t e coverage y i e l d s i m i l a r e ~ i d e n c e . ~ An energy l o s s mechanism h a s been used t o p a r t i a l l y e x p l a i n t h e e n e r g y d i s t r i b u t i o n s o b t a i n e d . However, l i t t l e of p o s i t i v e n a t u r e can be l e a r n e d o f t h i s , and o t h e r l o s s mechanisms which may be i n v o l v e d , b y s t u d y i n g t h e e n e r g y d i s t r i b u t i o n o f e l e c t r o n s emerging from t h e s u r f a c e o f a s o l i d which i s s t i m u l a t e d by e i t h e r t h e Auger o r p h o t o - e l e c t r i c p r o c e s s .
which i s produced w i t h i n t h e s o l i d by e i t h e r t h e Auger o r t h e photo- e l e c t r i c p r o c e s s i s v e r y b r o a d , t h e w i d t h o f t h e e l e c t r o n e n e r g y d i s - t r i b u t i o n b e i n g o f e q u a l magnitude t o t h e maximum e l e c t r o n e n e r g y i n v o l v e d .
n o t b a - r e s o l v e d and can o n l y b e d e t e c t e d by t h e s h i f t s which t h e y c a u s e i n t h i s b r o a d e n e r g y d i s t r i b u t i o n .
The e l e c t r o n energy d i s t r i b u t i o n
Thus, any e n e r g y l o s s mechanism which may be p r e s e n t w i l l
The e l e c t r o n energy l o s s mechanism invoked t o e x p l a i n t h e d i f f e r e n c e between t h e Auger d i s t r i b u t i o n f o r a c l e a n W s u r f a c e and t h a t o f a W s u r f a c e w i t h a gas a d s o r b e d i s 3 t h a t , when e l e c t r o n s o r i g i - n a t i n g from t h e Auger p r o c e s s r e a c h t h e s u r f a c e o f t h e s o l i d , some
s t i m u l a t e e l e c t r o n s i n t h e ground s t a t e l e v e l s o f t h e adsorbed g a s t o jump t o h i g h e r l e v e l s . I n t h i s p r o c e s s , t h e energy o f t h e Auger e l e c - t r o n i s lowered by a d i s c r e t e amount U , t h e energy which i s t a k e n up by t h e e l e c t r o n a s s o c i a t e d w i t h t h e adsorbed g a s atom o r m o l e c u l e . The n e t v i s i b l e e f f e c t o f t h i s upon t h e Auger e l e c t r o n e n e r g y d i s t r i b u t i o n of a c l e a n s u r f a c e i s a d e c r e a s e i n t h e d i s t r i b u t i o n a t t h e h i g h e n e r g y
‘C. N. Berglund, Tech. Rep. No. 5205-1, C e n t e r f o r M a t e r i a l s Research.
10
end and a n i n c r e a s e i n t h e d i s t r i b u t i o n i n t h e lower energy r e g i o n . F u r t h e r , s i n c e a l l Auger e l e c t r o n s which e x c i t e e l e c t r o n s o f t h e ad-
sorbed g a s must be d i s p l a c e d i n t h e e n e r g y d i s t r i b u t i o n t o a p o i n t o f e n e r g y a t l e a s t t h e amount U below t h e i r o r i g i n a l e n e r g y , t h e d i s t r i b u - t i o n s f o r c l e a n and gas-adsorbed s u r f a c e s should be o f t h e same shape
(one s h o u l d be a b l e t o g e t one from t h e o t h e r by simply u s i n g t h e c o r - r e c t m u l t i p l y i n g f a c t o r ) from t h e h i g h e n e r g y c u t - o f f , E o , down t o e n e r g y Eo-U. T h i s i s found t o be t r u e e x p e r i m e n t a l l y . A l s o , i t i s i n d i c a t e d t h a t t h e m u l t i p l i e r n e c e s s a r y t o make t h e adsorbed-gas Auger d i s t r i b u t i o n c o i n c i d e w i t h the c l e a n - s u r f a c e Auger d i s t r i b u t i o n i n t h e r a n g e from Eo-U t o Eo i s d i r e c t l y p r o p o r t i o n a l t o t h e a d s o r b a t e c o v e r a g e .
The same mechanism can be used t o e x p l a i n t h e d i f f e r e n c e between t h e p h o t o - e l e c t r i c d i s t r i b u t i o n f o r a c l e a n and an a b s o r b a t e covered s u r f a c e .
There a r e many energy l o s s mechanisms o t h e r t h a n t h e elec- t r o n i c t r a n s i t i o n s o f an adsorbed g a s which a l s o make d i s c r e t e e l e c t r o n energy l o s s t r a n s i t i o n s p o s s i b l e . However, most of t h e s e cannot be
" t u r n e d on" and " t u r n e d o f f " by a d s o r b i n g and f l a s h i n g - o f f an a d s o r b a b l e g a s a s can t h e e l e c t r o n i c t r a n s i t i o n s o f an adsorbed g a s , so t h a t t h e i r s h i f t i n g e f f e c t on t h e broad energy d i s t r i b u t i o n o f t h e Auger and photo- e l e c t r i c p r o c e s s c a n n o t be d e t e c t e d ; n e v e r t h e l e s s , i t i s q u i t e l i k e l y t h a t t h e y a r e p r e s e n t .
c a u s e e l e c t r o n energy l o s s e s a r e t h e f o l l o w i n g :
Some of t h e e n e r g y - l o s s mechanisms which c o u l d
11
I I I I 1 I I I 1 I I i I I 1 I I I I
A. S t u d i e s by Gomer5 on s u r f a c e i o n i z a t i o n o f adsorbed CO i n d i c a t e t h a t m o l e c u l a r v i b r a t i o n l e v e l s can be e x c i t e d , S i n c e t h e s e a r e s e p a r a t e d by o n l y roughly 1/10 v o l t , t h e y w i l l be even more d i f f i - c u l t t o "see" t h a n t h e a d s o r b a t e e l e c t r o n i c l e v e l s which have l e v e l s e p a r a t i o n s o f r o u g h l y 10 v o l t s . Suppose t h a t t h e a d s o r b a t e was s t i m u - l a t e d by a "monochromatic" e l e c t r o n beam o f t o t a l h a l f w i d t h 1 / 4 5 v o l t i n c i d e n t o n t a r g e t s u r f a c e and t h a t t h e r e s u l t a n t " r e f l e c t e d " beam was e n e r g y a n a l y z e d w i t h t h e same 1 / 4 5 v o l t r e s o l u t i o n , t h e n one h o p e f u l l y s h o u l d be a b l e t o s e e a s e t o f peaks s e p a r a t e d from t h e i n c i d e n t e n e r g y by t h e v i b r a t i o n a l energy l e v e l s e p a r a t i o n s ( s i n c e t h e o v e r - a l l e n e r g y r e s o l u t i o n i s less t h a n 1/25 v o l t which i s l e s s t h a n 1/10 v o l t ) .
B . I n semiconductors, s t u d i e s o f s u r f a c e c o n d u c t i o n have e s t a b l i s h e d t h e e x i s t e n c e of " p o t e n t i a l troughs" a t t h e s u r f a c e o f t h e semiconductor. The e x i s t e n c e o f t h e s u r f a c e s t a t e s i n t h e s e p o t e n t i a l t r o u g h s , t h e i r w i d t h , and t h e i r e x a c t l o c a t i o n could be f u r t h e r e s t a b - l i s h e d by u s i n g t h e same t e c h n i q u e s u g g e s t e d above f o r t h e s t u d y o f t h e v i b r a t i o n l e v e l s o f adsorbed CO.
C . Acceptor and donor l e v e l s p r o v i d e e n e r g y l e v e l s which make d i s c r e t e e l e c t r o n - e n e r g y loss t r a n s i t i o n s p o s s i b l e , Even though t h e s e l e v e l s a r e i n t h e bulk m a t e r i a l , t h i s c o u l d p o s s i b l y be s t u d i e d a s s u g g e s t e d i n A and B .
5 R . Gomer and L . Swanson, J . Chem. Phys.
2,
2833 (1963).I I I I 1 I I I I
' I
I II
I I 1 I I I 1
12
D. The f i r s t , second, and e t c . , f i l l e d bands below t h e con- d u c t i o n band of a m e t a l p r o v i d e energy l e v e l s which can c a u s e e l e c t r o n s i n an i n c i d e n t beam t o l o s e energy. S e v e r a l t y p e s o f e l e c t r o n energy t r a n s i t i o n o c c u r i f t h e i n c i d e n t beam h a s enough e n e r g y t o e x c i t e elec- t r o n s from t h e s e f i l l e d bands: ( a ) t h e e l e c t r o n i n i t i a l l y e x c i t e d may be s e t f r e e o r end-up i n t h e c o n d u c t i o n band; ( b ) a n e l e c t r o n from t h e c o n d u c t i o n band w i l l f a l l i n t o t h e h o l e e x c i t i n g an Auger e l e c t r o n from t h e c o n d u c t i o n band; ( c ) e t c .
2 . 3 . 2 Experimental A p p a r a t u s . The e x p e r i m e n t a l a p p a r a t u s proposed and now under c o n s t r u c t i o n t o s t u d y t h e s e e n e r g y l o s s mechan- i s m s i s a s e t o f e l e c t r o s t a t i c e n e r g y a n a l y z e r s and t h e n e c e s s a r y re- l a t e d a p p a r a t u s . The e l e c t r o s t a t i c energy a n a l y z e r s shown i n F i g u r e 2 . 1 c o n s i s t i n e s s e n c e o f p o r t i o n s o f c o n c e n t r i c c y l i n d e r s w i t h a d i f f e r - e n c e o f p o t e n t i a l between. The magnitude o f t h e p o t e n t i a l between t h e two p o r t i o n s o f c y l i n d e r s d e t e r m i n e s t h e e n e r g y o f t h e e l e c t r o n s t h a t can p a s s t h r o u g h t h e a n a l y z e r . The w i d t h o f t h e s l i t s a t e i t h e r end o f a n a n a l y z e r d e t e r m i n e s t o a l a r g e d e g r e e t h e e n e r g y r e s o l u t i o n o f t h e a n a l y z e r .
b e i n g c o n s t r u c t e d i s 2AV/V = 1/45.
The optimum energy r e s o l u t i o n o f e a c h o f t h e a n a l y z e r s
A s i n g l e c r y s t a l of t u n g s t e n w i l l be t h e f i r s t t a r g e t used.
A c a r e f u l e n e r g y a n a l y s i s o f t h e e l e c t r o n s " r e f l e c t e d " from t h e s u r f a c e o f t h e t a r g e t a s i t i s bombarded w i t h "monochromatic" e l e c t r o n s f o r b o t h c l e a n and g a s a d s o r b e d t a r g e t s should a l l o w one t o make some d i r e c t and meaningful s t a t e m e n t concerning t h e e n e r g y loss mechanisms a t work.
I I I I I I I I I I I I 1 I I I I I I
13
E l e c t r o s t a t i c Energy Analysers
/ \
I 1
m Xtal Target U
Electron Source Cur rent Detector
Figure 2.1. Schematic of Electron Scattering Apparatus.
14
I I I I I I I I I I I I I I I I D I
m
2 . 4 T o t a l Cross-Sections f o r S c a t t e r i n g and f o r I o n i z a t i o n o f Barium Atoms by Low Energy E l e c t r o n s
Very l i t t l e d a t a e x i s t s i n t h e l i t e r a t u r e on t h e p r o p e r t i e s o f barium a s a plasma c o n s t i t u e n t . No r e f e r e n c e h a s been found, f o r i n s t a n c e , t o measurements of c o l l i s i o n c r o s s - s e c t i o n s o r t o e x c i t a t i o n f u n c t i o n s . T h i s l a c k o f i n f o r m a t i o n about barium and o t h e r a l k a l i n e e a r t h e l e m e n t s may be a s c r i b e d t o t h e i r low vapor p r e s s u r e s a s compared t o t h e a l k a l i e s and t o z i n c , cadmium, and mercury, a l l of which have been s t u d i e d i n some d e t a i l . However, advances i n m a t e r i a l s technology have made i t p o s s i b l e t o c o n t a i n barium v a p o r , and an e x p e r i m e n t a l barium-plasma d e v i c e was r e p o r t e d r e c e n t l y by Kennedy, S h e f s i e k , and T a l a a t . T h i s i s a thermionic energy c o n v e r t e r i n which barium i o n s a r e employed t o n e u t r a l i z e the e l e c t r o n i c space-charge. The r e s u l t s show t h a t t h e i o n i z a b i l i t y of barium v a p o r , a l t h o u g h n o t a s g r e a t a s f o r cesium v a p o r , i s s u f f i c i e n t t o p r o v i d e t h e i o n s needed f o r n e u t r a l i - z a t i o n i n a t h e r m i o n i c c o n v e r t e r . The d e g r e e o f i o n i z a t i o n i s sub- s t a n t i a l l y g r e a t e r t h a n p r e d i c t e d from t h e i o n i z a t i o n p o t e n t i a l and t h e Saha-Langmuir formula. This s u g g e s t s t h a t t h e m e t a s t a b l e s t a t e s i n barium, f o r which s p e c t r o s c o p i c e v i d e n c e e x i s t s , must p l a y an i m p o r t a n t r o l e i n producing t h e i o n s . However, t h i s r o l e w i l l remain
6
e s s e n t i a l l y s p e c u l a t i v e u n t i l c e r t a i n fundamental d a t a a r e o b t a i n e d . The immediate o b j e c t i v e o f t h i s i n v e s t i g a t i o n i s t o o b t a i n e x p e r i m e n t a l
6A. J. Kennedy, P. K. S h e f s i e k , and M. E . T a l a a t (Martin Company, Nuclear D i v i s i o n ) , ” R e s e a r c h and Development f o r Barium Vapor- F i l l e d Thermionic Energy Conversion Technology.”
MND-2933-2 (May, 1964)
Summary Report
I 1 1 I I B I I
8 3
1 1 I I I
I
I 1 U
e
15
i n f o r m a t i o n on t o t a l c o l l i s i o n c r o s s - s e c t i o n s f o r s c a t t e r i n g and f o r i o n i z a t i o n o f barium atoms i n c o l l i s i o n s w i t h l o w e n e r g y e l e c t r o n s . P l a n s have been made f o r e x t e n d i n g t h e i n v e s t i g a t i o n t o i n c l u d e e x c i t a - t i o n c r o s s - s e c t i o n s o f t h e m e t a s t a b l e s t a t e s a t an a p p r o p r i a t e t i m e .
An a t o m i c beam method w i l l be used i n t h e s t u d y . The e s s e n c e o f t h e method i s i l l u s t r a t e d s c h e m a t i c a l l y i n F i g u r e 2.2. A narrow beam o f barium atoms i s produced by an oven and c o l l i n a t i n g s l i t . beam i s c r o s s - f i r e d by a s t r e a m o f slow e l e c t r o n s o f known e n e r g y , t h e r e b y producing s c a t t e r i n g of b o t h e l e c t r o n s and barium atoms, and i n a d d i t i o n e x c i t a t i o n and i o n i z a t i o n when t h r e s h o l d e n e r g i e s a r e exceeded.
The
The t o t a l c r o s s - s e c t i o n f o r i o n i z a t i o n i s t h e s i m p l e s t from t h e v i e w p o i n t o f d e t e c t i o n . A s u i t a b l e p o s i t i v e i o n c o l l e c t o r can be used t o c o u n t t h e i o n s .
The t o t a l c r o s s - s e c t i o n f o r s c a t t e r i n g by slow e l e c t r o n s w i l l be d e t e r m i n e d by a method similar t o t h a t u s e d by Rubin, P e r e l , Bederson and Englander i n measurements o f c r o s s - s e c t i o n s o f a l k a l i atoms.'
t h e a c c e p t a n c e w i d t h o f the beam d e t e c t o r i s l e s s t h a n t h e beam w i d t h , s c a t t e r i n g c o l l i s i o n s d e p l e t e t h e d e t e c t e d beam i n t e n s i t y , t h e r e b y p e r - m i t t i n g t h e c o l l i s i o n s t o be c o u n t e d . A s u r f a c e i o n i z a t i o n d e t e c t o r
d e s c r i b e d by Hay
I f
8 w i l l be used t o d e t e c t t h e barium atoms.
7Phys. Rev.
-
1 1 7 , pp. 151-158 (1960), and Phys. Rev.128,
pp. 1148-1154 (1962).
8R. H. Hay, "The Nuclear Magnetic Moments o f C 1 3 , Ba135 and Ba137,11 Phys. Rev.
60,
pp. 75-86 (1941).I I 1 8 1
I)
D I 1
c
1
E
I
t
E
I
I I
I
16
A t o m i c b e o m
LOW energy d e t e c t o r
e l e c t r o n s
a t o m s
Figure 2.2. Schematic of the Apparatus for the Study of the Electron Scattering from Barium Atoms.
17
C l o s e c o n t r o l o f s u r f a c e c o n d i t i o n s i s e s s e n t i a l f o r t h e func- t i o n i n g o f t h e s u r f a c e i o n i z a t i o n d e t e c t o r and f o r t h e d e t e c t i o n scheme under c o n s i d e r a t i o n f o r m e t a s t a b l e barium atoms. The i n v e s t i g a t i o n o f s u r f a c e e f f e c t s i n t h e s e d e t e c t o r s i s an i m p o r t a n t a s p e c t o f t h e program.
Consequently, t h e s t u d y w i l l b e c a r r i e d o u t under u l t r a h i g h vacuum c o n d i t i o n s
.
P r e l i m i n a r y p l a n s have been made f o r t h e e n t i r e s t u d y . C o n s t r u c t i o n of components o f t h e a p p a r a t u s w i l l be s t a r t e d s h o r t l y .
R. R e t h e r f o r d
3.
E
I
I
I I
4 2
e
I I t
I
!
I I
T P
I
R.
M. Brown S. Fenves
18
3 .
COMPUTER
RESEARCHAPPLICATIONS
R.Trogdon
3.
Stifle
R.
Jenks
3 . 1
Introduction
This group is concerned with the design and applications of digital computers for information processing, primarily in the areas of real-time and non-numerical operations. The present work concerns
the development
o fan experimental time-sharing system and studies in the applications of computers in experimental physics.
3 . 2
Logical Design
The designer of digital data processing equipment invariably finds himself dealing with Boolean expressions which describe the func- tions and operations performed by the equipment.
these expressions may be simplified, yielding simpler and more economi- cal circuits. Although there are many well known techniques for simpli- fying Boolean expressions, even the best
o fthese techniques can be quite time consuming, especially if a large number of variables is involved .
More often than not,
To
eliminate this time-consuming operation, a program has been written for the CSX-1 which can be used to simplify Boolean expres-
sions containing up to eight variables. The program uses the iterated
consensus technique first described by Shannon and Mills.
19
A d e s c r i p t i o n o f t h i s t e c h n i q u e may b e found i n "Theory and Design o f D i g i t a l Machines," by B a r t e e , Lebow, and Reed, Chapter 4 , S e c t i o n s 4.1 t o 4.8.(McGraw-HillY 1962).
J.
S t i f l e 3 . 3 The DIOG Experimental Time-sharing S y s t e mDuring t h e p r e v i o u s q u a r t e r , hardware h a s been i n s t a l l e d i n t h e CSX-1 t o h a n d l e t h e communication between 7094 and t h e CSX-1 f o r t h e proposed DIOG system ( s e e P r o g r e s s Report f o r March, A p r i l , May, 1964). T h i s equipment employs f i v e CSX-1 i n p u t - o u t p u t c h a n n e l s ; t h r e e c h a n n e l s p r o v i d e f o r d a t a t r a n s f e r t o and from t h e 36-bit-word memory of t h e 7094 w h i l e t h e o t h e r two c h a n n e l s a r e u s e d f o r c o n t r o l informa-
t i o n .
7094 system w r i t t e n by t h e D i g i t a l Computer L a b o r a t o r y , e l i m i n a t i n g t h e need f o r any s p e c i a l program i n t e r f a c e between t h e 7094 system program
T h i s equipment makes t h e DIOG system c o m p a t i b l e w i t h t h e e x i s t i n g
and t h e i n p u t - o u t p u t c h a n n e l s .
The Phase Zero DIOG Program has been completed and checked o u t by s i m u l a t i o n . I n Phase Zero, t h e u s e r o p e r a t e s i n one o f two modes. I n t h e e x e c u t i v e mode, a d i a l o g u e i s c a r r i e d o u t between t h e user a t t h e c o n s o l e f l e x o w r i t e r and t h e CSX-1 f o r t h e purpose o f s p e c i - f y i n g and a c t i v a t i n g a d e s i r e d f u n c t i o n a l program i n t h e 7094. Four d i r e c t i v e s o r commands may be g i v e n t o t h e DIOG c o n t r o l program i n t h e e x e c u t i v e mode: "LOGIN" i n i t i a t e s a d i a l o g u e ; "CALL" e n a b l e s t h e u s e r t o s p e c i f y a n o n - l i n e f u n c t i o n a l program; ''TERMINATE" i s used t o t e r m i - n a t e t h e d i a l o g u e w i t h t h e p r e v i o u s l y c a l l e d f u n c t i o n a l program;
"LOGOUT" c l o s e s o u t a d i a l o g u e .
20
Following t h e e s t a b l i s h m e n t of a program, t h e u s e r and CSX-1 e n t e r t h e program mode where t h e CSX-1 t r a n s m i t s messages back and f o r t h between 7094 and t h e u s e r . Here messages a r e accumulated by t h e CSX-1 and monitored f o r one o f two s i g n a l s : (1) a " c a r r i a g e r e t u r n " c h a r a c - t e r which c a u s e s t h e t r a n s m i s s i o n o f t h e p r e v i o u s l y e n t e r e d l i n e t o t h e 7094; ( 2 ) a "STOP" c h a r a c t e r f l e x o w r i t e r which produces a t r a n s f e r o f t h e d i a l o g u e back t o t h e e x e c u t i v e mode. F u r t h e r d e t a i l s of t h e DIOG system a r e g i v e n by i n t e r n a l memo D 2 .
I n i t i a l Phase Zero checkout w i t h t h e 7094 w i l l i n v o l v e o n l y d a t a t r a n s m i s s i o n s between t h e two computers w i t h t h e m o n i t o r system i n t h e 7094 s i m u l a t e d i n t h e CSX-1. F u r t h e r Phase Zero checkout a w a i t s changes i n t h e e x i s t i n g 7094 e x e c u t i v e system which w i l l a l l o w t h e 7094 t o o p e r a t e e i t h e r i n t h e o n - l i n e mode o r t h e c o n v e n t i o n a l b a t c h
p r o c e s s i n g mode.
R. M. Brown R . J e n k s 3.4 SMP Bubble Chamber Data P r o c e s s i n q
The SMP measuring c o n s o l e h a s been moved t o the P h y s i c s B u i l d i n g and a communication l i n e t o t h e CSX-1 computer i n s t a l l e d . I n t h e coming months t h r e e more u n i t s w i l l be added and m u l t i p l e x e d t o t h e CSX-1. The measuring program, DMSCAMP, i s i n t h e p r o c e s s o f m o d i f i c a t i o n t o p e r m i t measurements on f i l m from t h e Argonne 30" chamber
c o n c u r r e n t w i t h measurements on B e r k e l e y 72" chamber f i l m . S i g n i f i c a n t improvements have been made i n t h e a c c u r a c y of t h e d a t a p r o c e s s i n g and t h e i n c o r p o r a t i o n o f c o n s o l e d i a g n o s t i c p r o c e d u r e s .
R. M. Brown
Circ. & Cormnun,
M. E. Van Valkenburg J . K. Aggarwal
R. B. Ash D. H. Cooper P. Ponzo R . A. Rohrer N. Wax
21
4. SYSTEMS
Control Systems J. B. Cruz, J r . S. D. Agashe D. G i e s e k i n g T. E. M u e l l e r T. Murata W . R. P e r k i n s R . A. Rohrer D. Snyder G . Tahim R. Werner
Switch. Systems S . Seshu
K. E. B a t c h e r A. D e r v i s o g l u G . Dodd
B. E l l i o t t W . Mayeda K . Onaga A. P a u l J . A . Resh H .
Y.
Chang4.1 G e n e r a t i o n of Trees w i t h o u t D u p l i c a t i o n
One o f t h e i m p o r t a n t problems i n t h e i m p l e m e n t a t i o n o f computer methods o f network a n a l y s i s i s t h e g e n e r a t i o n of t h e trees of a l i n e a r g r a p h w i t h o u t d u p l i c a t i o n . F u r t h e r , i n o r d e r t o b e a b l e t o compute the s i g n o f a t r e e (which h a s t o b e done i n t h e a n a l y s i s of a c t i v e networks) t h e t r e e s must be g e n e r a t e d by r e p l a c e m e n t o f one b r a n c h a t a t i m e . A tree g e n e r a t i o n scheme s a t i s f y i n g t h e s e r e q u i r e m e n t s h a s been o b t a i n e d and h a s been r e p o r t e d i n r e p o r t number R-220. I n t h i s p r o c e d u r e d u p l i - c a t i o n s a r e avoided by two d e v i c e s . On t h e one h a n d , w e a r r a n g e t h e b r a n c h e s of t h e s t a r t i n g t r e e i n t o an o r d e r e d sequence such t h a t any l e a d i n g s u b s e t o f b r a n c h e s i n t h e sequence c o n s t i t u t e s a c o n n e c t e d sub- graph. On t h e o t h e r , w e r e q u i r e t h a t any l i n k which r e p l a c e s a branch o f t h e p r e s e n t t r e e belong not o n l y t o t h e fundamental c u t - s e t o f t h e r e p l a c e d b r a n c h w i t h r e s p e c t t o t h e p r e s e n t t r e e (which i s n e c e s s a r y i n o r d e r t h a t t h e new s e t o f b r a n c h e s be a t r e e ) b u t a l s o t o t h e funda- m e n t a l c u t - s e t o f t h e b r a n c h w i t h r e s p e c t t o t h e s t a r t i n g t r e e . The
22
r e p l a c e m e n t i s a l s o o r d e r e d l e f t t o r i g h t i n t h e o r d e r e d sequency r e p r e - s e n t a t i o n of t h e s t a r t i n g t r e e . It has been shown t h a t t h i s scheme g e n e r a t e s a l l t h e t r e e s of the g r a p h and no t r e e i s g e n e r a t e d more t h a n once.
The d e t a i l e d procedure and t h e p r o o f s o f t h e a s s e r t i o n s above a r e t o be found i n t h e c i t e d r e p o r t .
W. Mayeda S . Seshu 4.2 Q u a s i - L i n e a r S e q u e n t i a l Machines
The i n v e s t i g a t i o n on t h e r e a l i z a b i l i t y of q u a s i - l i n e a r s e q u e n t i a l machines has been completed. A n e c e s s a r y and s u f f i c i e n t c o n d i t i o n was o b t a i n e d f o r a g i v e n c o n n e c t i o n m a t r i x ( o r a s t a t e d i a - gram), w i t h t h e g i v e n encoding of s t a t e s , t o be r e a l i z a b l e a s a q u a s i - l i n e a r s e q u e n t i a l machine making u s e o f minimal number o f feedback l i n e s . A l s o o b t a i n e d was a c a n o n i c a l r e a l i z a t i o n which e n a b l e s one t o r e a l i z e any a r b i t r a r y s t a t e diagram a s a q u a s i - l i n e a r s e q u e n t i a l machine u s i n g a s u f f i c i e n t l y l a r g e number o f memory e l e m e n t s . These r e s u l t s
a r e d i s c u s s e d i n d e t a i l i n Report R-216.
The i n v a r i a n t p r o p e r t i e s o f t h e s t a t e diagram o f q u a s i - l i n e a r s e q u e n t i a l machines, w i t h respect t o t h e change o f coding o f s t a t e s , a r e b e i n g s t u d i e d .
H. Y. Chang 4 . 3 S e l f - D i a g n o s i s
Work h a s been s t a r t e d on a problem o f s e l f - d i a g n o s i s ; t h e o b j e c t o f s t u d y i s t h e l a b o r a t o r y ' s CSX-1 computer. I n i t i a l a t t e m p t s
