study  Guide:  and  korkbook 
G3A2R991C5.    GQO-V 
Technical  Training 
Scientific  Measurements  Technician 
INTRODUCTION  TO  DETECTION   SYSTEMS 
18  October  1934 
■  i 
.-*  r 
340G  technical  training  wing 
3454  School  Squadron 
Lcwrv  Air  Force  Ease,  Colorado 
Desicr.ec  for  ATC  Course  Use 
DO  NOT  USE  ON  THE  JO 3
34  00TH  TECHNICAL  TRAINING  WING 
3454th  School  Squadron 
Lovry  Air  Force "Ease,  Colorado 
sw  G3A3r;;io:  coo- 
13  October  1984 
Study  Guides  (SG) ,  Workbooks  (W3s),  Study  Guides  and  Workbooks 
(SWs),  Programmed  Texts  (PTs),  Student  Texts  (STs),  and  Handouts 
{HO s)    are  authorized  by  ATC  for  student  use  in  ATC 'courses.   They 
art-  designed  to  guide  you  through  your  study  assignments  in  the 
mvst  logical  sequence  for  easy  understanding.   Answer  the  self 
evaluation  questions  end  complete  each  problem  or  work  assignment 
in  the  sequence  given,  and  it  will  aid  you  in  understanding  and 
retaining  the  key  points  covered  in  material  you  have  studied. 
CONTENTS 
Unit  Title 
Purpose   .' 
 ...»    i 
I  Detection  Systems   1 
II  Geognosy.   -   23 
III  Wave  Propagation. . . . ." 
This  document  has  keen  reviewed  by  the  Unit  Security  Manage: 
ar.i  the  fcllcv/ir.g  classification  has  'been  assigned: 
   VtitLA^rprfeT)   
iS.-.a..u=._.  jQrr/L  (i.ryiiu.        
Classification 
S 
Date  cf  Review 
2  9  OCT  1924
Instruction  Section  SW  G3ABR99105   000-V-2 
Lov/ry  Air  Force  Base,  Colorado  18  October  1984 
DETECTION   SYSTEMS 
OBJECTIVES 
O        From  five  statements  select  only  those  statements  describing  significant 
events  in  the  history  and  development  of  detection  systems  utilized  by 
AFTAC.       ■      - 
o   Complete  five  statements  describing  the  ooeratiqnal  con- 
cepts of  detection  systems  employed  by  AFTac. 
o   Match  four  detection  systems  employed  by  AFTAC  to  a  sta- 
tement depicting  how  it  contributes  to  mission         .. 
accomplishment.  "** 
INTRODUCTION 
This  unit  of  instruction  is  designed  to  familiarize  you  with 
the  detection  systems  employee  by  AFTAC.  The  materials  presented 
are  an  overview  of  the  history  and  development  of  monitoring 
systems,  the  operational  concept  of  current  systems,  and  the 
contributions  each  make  to  mission  accomplishment. 
It  is  hoped  that  this  unit  will -instill  a  sense  of  mission 
importance  and  spur  you  to  study  the  impact  of  nuclear  weapons 
•develooment  on  the  policies  of  all  nations. 
The  history  and  development  of  the  detection  systems  employed 
bv  AFTAC  are  closely  linked  to  the  proliferation  of  nuclear 
uowec.  The  U.S.  was  the  first  to  detonate  a  nuclear  device  and 
the  first  to  establish  a  network  of  monitoring  systems. 
Ironically,  as  we  will  see,  many  of  the  same  individuals  who 
developed  the  atomic  bomb  are  also  the  staunchest  supporters  of  a 
nuclear  freeze. 
INFORMATION 
HISTORY  AND  DEVELOPMENT 
The  Nuclear  Club. 
C.t  the  morning  of  July  16,  1945,  in  the  desert  near^ 
Al^agordo,  N.M.  an  event  occurred  that  will  dominate  history 
forever.   The  United  States  successfully  completed  the  largest 
lab^r-iory  exoeriment  ever  attempted;  the  detonation  of  the  first 
nuclear  device.   Code-named  Trinity,  the  test  culminated  the  most 
intens-i  research  and  development  program  ever  undertaken.
During  the  years  1943  through  1945  more  than  10,000  people 
were  gathered  at  a  converted  boys  school  near  the  desert 
community  of  Santa  Fef  New  Mexico.  The  Los  Alamos  Laboratory, 
under  the  direction  of  Dr.  J.  Robert  Oppenheimer,  was  established 
there  and  tasked  to  develop  a  weapon  of  awesome  destructive 
power.   Physicists  from  around  the  world  worked  night  and  day  on 
what  was  termed  the  "Manhattan  Project". 
Despite  common  perception,  the  thought  of  such  a  weapon  was 
by  no  means  a  new  idea.  As  early  as  August  1939,  Dr.  Albert 
Einstein,  in  a  letter  to  President  Roosevelt  stated,  in  part  "it 
may  become  possible  to  set  up  a  nuclear  chain  reaction  in  a  large 
mass  of  uranium,  by  which  vast  amounts  of  power  and  large 
quantities  of  new  radium-like  elements  would  be  generated   
This  new  phenomenon  would  also  lead  to  the  construction  of  bombs, 
and  it  is  conceivable,  though  less  certain,  that  extremely 
powerful  bcubs  oc   a  new  type  may  thus  be  constructed".   Dr. 
Einstein's  letter  caught  the  respectful  interest  of  Mr.  Roosevelt 
and  truly  launched  tha  United  States  effort  to  build  an  atomic 
bomb. 
The  power  of  such  a  weapon  was  demonstrated  to  the  world  on 
August  6,  1945  at  Hiroshima,  Japan.  On  that  day  more  than  70,000 
people  lost  their  lives  and  62,000  of  the  city's  90,000  buildings 
v/ere  reduced  to  rubble.   A  second  bomb  was  dropped  at  Nagasaki  on 
the  9th  of  August  and  the  war  in  the  Pacific  ended  on  the  15th. 
The  und  of  the  war  left  the  American  people  secure  with  the 
idea  that  no  other  country  could  produce  a  nuclear  weapon. 
Oppenheimer  himself  said  in  a  conversation  with  Dr.  Edward  Teller 
that  "We  have  done  a  wonderful  job  here  (Los  Alamos) ,  anJ  it  will 
be  many  years  before  anyone  can  improve  on  our  work  in  any  way." 
Soon,  stark  realizations  began  to  chip  away  this  false 
security.  Politicians  began  to  "recognize  that  many  of  the 
physicists -involved  in  the  development  of  the  atomic  bomb  were 
European  born.  Moreover  Russia  was  not  willing  to  accept  a  plan 
that  the  U.S.  proposed  to  the  United  Nations.  This  plan  would 
have  placrd  control  of  nuclear  development  in  the  hands  of  an 
international  committee  and,  in  effect,  made  our  knowledge 
available  to  anyone.  Finally,  it  was  revealed  that  a  group  of 
Japanese  pnysicists  had  tried  unsuccessfully  to  produce  an  atomic 
weapon  toward  the  end  of  the  war.  Reports  to  the  Japanese 
government  in  early  1945  stated  that  major  obstacles  had  been 
overcome  and  more  critical  experiments  were  to  begin. 
Awareness  that  other  countries  could,  and  eventually  would, 
develop  nuclear  capability  led  to  the  subsequent  endorsement  of 
an  Atomic  Energy  Detection  System  (AEDS)  concept.   In  September 
1947,  Gen.  Dwight  D.  Eisenhower  directed  the  Army  Air  Forces  "to 
detect  atomic  explosions  anywhere  in  the  world."  This  task 
rei  ained  with  the  Air  Force  when  it  became  a  separate  service  (18 
September  1947}  and  was  vested  in  the  Air  Force  Technical 
Applications  Center  (AFTAC) .  Prior  to  being  AFTAC,  a  special 
task  force  within  the  Air  Force  was  assigned  to  "operate  and 
maintain  the  AEDS".
The  value  of  the  AEDS  was  proven  in  September  1949  when  an 
AFTAC  sensor  aboard  a  B29  detected  debris  from  the  first  Soviet 
atomic  test. 
This  detection  is  especially  noteworthy  since  most  experts 
had  predicted  that  the  first  Soviet  test  could  not  occur  before 
1951.   In  1949,  Western  scientists  and  politicians  did  not 
believe  that  the  Soviet  Union,  or  any  other  country,  was 
scientifically  sophisticated  enough  to  produce  atomic  weapons. 
This  was  a  mistake. 
Ardently  supported  atomic  physics  research  had  been  conducted 
in  the  USSR  for  many  years.   In  June  of  1944  the  Soviets  knew  the 
purpose  of  Los  Alamos.  By  June  of  45  they  were  aware  that  the 
first  test  was  scheduled  for  the  following  month,  and  by 
September  had  a  detailed  description  of  the  device  dropped  at   • 
Nagasaki.  Since  its  establishment,  a  vast  network  of  Soviet 
spies  had  been  collecting  every  available  piece  of  information 
about  the  operation  at  Los  Alamos  and  reporting  it  to  Moscow.  Of 
these,  Klaus  Fuchs  was  undoubtedly  the  most  important  to  their 
cause. 
Fi-chs  had. fled  Europe  and  Hitler's  Nazis  in  1933.  Eventually 
interned  in  Canada,  he  was  screened  and  released  in  1942  to  help 
with  Britain's  atomic  research.  He  became  a  full  fledged  member 
of  the  British  team  and  travelled  to  Los  Alamos  in  1944.  He 
worked  freely  at  the  laboratory  and  was  allowed  access  to  the 
facilities*  most  sensitive  secrets. 
A  friendly,  .quiet  man,  Fuchs  often  talked  at  great  length 
with  many  of  the  physicists  involved  in  the  project.  Throughout 
his  tenure,  he  relayed  all  he.  knew  to  a  soviet  spy,  Harry  Gold. 
It  is  ridiculous  to  believe  that  the  Soviets  could  not  have 
developed  atomic  weapons  without  the  information  provided  by 
Fuchs,  but~it  is  more  ridiculous  to  think  that  his  reports  did 
not  make  their  task  easier. 
On  August  7,  .1945,  the  day  after  Hiroshima,  Soviet  research 
intensified.  Convinced  that  atomic  weapons  could  be  constructed, 
Soviet  Premier  Joseph  Stalin  designated  his  chief  of  security, 
Lavrenti  Beria,  supervisor  of  atomic  research.  Beria  headed  a 
Russian  version  of  the  "Manhattan  Project"  that  resulted  in  the 
surface  detonation  of  a  device  in  the  Ust-urt  desert  on  August 
29,  1949. 
This  first  Soviet  test  was  followed  by  a  series  of 
unannounced  explosions  that,  by  the  summer  of  1953,  matched  the 
yield  of  on-going  American  tests. 
Since  the  40' s  four  other  countries  have  demonstrated  a 
nuclear  power,  reinforcing  the  need  for  an  AEDS. 
In  1952  Great  Britain  tested  an  atomic  bomb  in  a  small  group 
of  islands  off  the  west  coast  of  Australia.  They  continued  small 
atomic  tests  in  Australia  throughout  the  50' s,  and  in  1957  tested 
their  first  hydrogen  thermonuclear  device  at  Christmas  Island. 
the  British  continue  to  test  underground 
devices  at  the  Nevada  Test  Site  in  cooperation  with  the  United 
States.
During  the  50' s,  France,  under  the  leadership  of  General 
Charles  de  Gaulle,  began  to  strenghten  its  government  and  mili- 
tary.  By  the  mid  70' s  the  Array,  Navy,  and  Air  Force  were  to  be 
nuclear  armed. 
Beginning  in  1960,  and  continuing  through  1967  the  French 
conducted  surface  and  underground  tests  of  atomic  devices  in 
Algeria,  Africa.   However,  the  search  for  a  suitable  site  for 
fusion  bomb  testing  led  to  Mururoa  Atoll,  a  French  possession  in 
the  South  Pacific,  where  nuclear  testing  began  in  1966  and  con- 
tinues today. 
On  October  16,  1964  the  first  Chinese  nuclear  fission  device 
was  detonated  in  the  atmosphere  near  Lop  Nor,  Sinkiang  province. 
The  Chinese  nuclear  capability,  although  disputed,  was  heavily 
supported  by  Russion  technology.  Technical  assistance  from  the 
Soviets  began  in  1957  and  continued  until  1960  when,  due  to 
ideological  differences,  the  Soviets  withdrew  all  of  their  advi- 
sory forces.   The  Chinese  resolve  to  develop  a  nuclear  capability 
was  thus  strengthened.  Chairman  Mao  Tse-tung  summoned  his 
leading  physicists  and  directed  that  China  must  have  an  atomic 
weapon  by  January  1,  1965.  Obviously,  the  physicists  beat  their 
assigned  deadline. 
Finally,  on  May  18,  1974,  India  became  the  last  member  of 
the  nuclear  club.   Purportedly  constructed  with  only  Indian 
resources  the  device  provided  a  yield  of  10-15  kilotons. 
Immediately  following  the  test  the  chairman  of  the  Indian  Atomic 
Energy  Commission  announced  that  nuclear  devices  would  only  be 
used  for  peaceful  purposes  and  no  subsequent  tests  have  been 
recorded. 
Unfortunately,  the  members  of  the  nuclear  club  are  often  at 
odds.   The  fears  of  nuclear  proliferation  and  war  that  led  to  the 
creation  of.  an  AEDS,  and  subsequently  AFTAC,  have  sustained  both 
organizations  and  continues  to  upgrade  their  importance.   Over 
the  years,  many  attempts  to  dispel  .these  fears  have  resulted  in 
several  treaties  that  present  an  interesting  chronology. 
Treaties 
In  March  1946  the  first  workable  plan  for  control  of  atomic 
energy  was  made  public.   Originally  known  as  the  Acheson- 
Lilienthal  Report,  it  called  for  the  formation  of  an 
international  agency  to  monitor  atomic  energy.  The  agency  would 
control  all  of  the  world's  raw  materials,  operate  the  world's 
atomic  reactors,  and  license  the  raw  materials  necessary  for 
research.   This  report  was  presented  to  the  United  Nations  as  the 
Baruch  Plan  and,  as  mentioned  earlier,  met  stiff  opposition  from 
the  Soviets.  The  U.S.  was  trying  to  deal  with  a  commodity 
(knowledge  of  atomic  energy)  that  the  USSR  already  possessed. 
Additionally,  the  plan  required  on-site  inspection  to  insure 
compliance.  This  requirement  caused  dissent' throughout  the 
1950s.   Neither  side  of  the  debate  (US  and  USSR)  would  agree  on
the  number' of  inspections  to  allow.  This  single  issue  created  an 
impasse  that  lasted  until  the  early  1960's.  The  dawn  of  the 
1960s  brought  about  a  rash  of  treaties,  some  of  which  are  listed 
for  reference. 
ANTARCTIC  TREATY.   1961.  The  Antarctic  Treaty  bars  military 
activity,  including  nuclear  tests  in  Antarctica  and  is 
significant  in  that  it  was  the  first  multilateral  disarmament 
treaty  signed  after  WWII. 
The  treaty  prohibits  any  military  activities  in  Antarctica, 
such  as  establishing  bases,  conducting  maneuvers,  or  testing  any 
kind  of  weapon.   It  also  prohibits  exploding  nuclear  charges  and 
the  dumping  of  nuclear  wastes  south  of  60°  S.  latitude. 
To  verify  compliance  with  the  treaty  the  17  contracting 
parties  are  allowed  to  designate  observers  to  conduct  on-site 
inspections  at  any  time. 
LIMITED  TEST  BAN  TREATY  (LTBT) .  1963.   This  treaty  prohibits 
testing  nuclear  devices  in  the  atmosphere,  in  space,  and 
underwater.  Notably,  it  does  not  prohibit  underground  explosions 
but  does  ban  tests  that  would  cause  radioactive  debris  (fallout) 
outside  the  territory  where  the  explosion  is  conducted.  The 
treaty  has,  however,  lowered  the  level  of  high  yield  tests,-  made 
it  impossible  to  test  a  weapon  in  its  intended  environment,  and 
slowed  radioactive  contamination  of  the  atmosphere. 
Unfortunately,  the  treaty  does  not  specify  how  compliance  by 
the  106  contracting  parties  is  verified.  However,  there  have  to 
date  been  only  14  reported  violations,  8  by  the  Soviets  and  6  by 
the  US. 
Of  the  nuclear  powers,  China,  France:,  and  India  have  not 
signed  the -treaty  along  with  many  near-nuclear  states. 
OUTER  SPACE  TREATY.   1967.   The  Outer  Space  Treaty  prohibits 
placing  nuclear,  as  well  as  other  kinds  of  weapons  of  mass 
destruction,  in  earth  orbit  and  limits  the  use  of  the  moon  and 
other  celestial  bodies  to  peaceful  purposes.  Additionally,  the 
treaty  prohibits  establishment  of  military  bases,  testing  of  any 
kind  of  weapon,  and  military  maneuvers  on  celestial'  bodies. 
The  71  signatories  of  this  treaty  have  since  the  early  60  "s 
voluntarily  registered  all  objects  launched  into  space.  This  act 
is  in  accordance  with  the  principle  of  the  treaty  stating  that 
states  bear  international  responsibility  for  national  activities 
in  outer  space. 
LATIN  AMERICAN  NUCLEAR  FREE-ZONE  TREATY.   1968.  This  treaty 
bans  nuclear  weapons  from  Latin  America.  The  treaty  aims  at 
making  Latin  America  a  nuclear-free  zone  and  prohibits  "testing, 
use,  manufacture,  production  or  acquisition!  by  any  means  as  well 
as  receipt,  storage,  deployment,  and  any  form  of  possession  of 
nuclear  weapons  by  countries  in  Latin  America".  One  article
defines  a  nuclear  weapon  as  "any  device  which  is  capable  of 
releasing  nuclear  energy  in  an  uncontrolled  manner  and  which  has 
a  group  of  characteristics  that  are  appropriate  for  use  for 
warlike  purposes". 
There  is  some  dissent  over  the  right  to  conduct  peaceful 
nuclear  explosions,  however,  overall  the  treaty  is  honored.  An 
organization  (Agency  for  Prohibition  of  Nuclear  Weapons  in  Latin 
America)  has  been  established  to  ensure  compliance  with  the 
treaty. 
NON-PROLIFERATION  TREATY  (NPT) .   1970.   This  treaty  bars 
supplying  nuclear  weapons  to  non-nuclear  states.  Basically,  the 
treaty  stops  the  spread  of  nuclear  weapons  and  aims  at  limiting 
the  number  of  nuclear  countries  to  those  having  nuclear  weapons 
in  1967.  Nuclear  weapon  states,  defined  by  the  treaty  as  those 
states  having  carried  out  a  nuclear  explosion  prior  to  1967,  are 
prevented  from  assisting  non-nuclear  states  in  acquiring  nuclear 
devices.  Additionally,  a  non-nuclear  weapon  state  party  to  the 
treaty  is  prohibited  from  manufacturing  nuclear  devices.  They 
may,  however,  make  the  necessary  preparations  for  the  manufacture 
of  nuclear  weapons  without  violating  the  treaty. 
All  parties  to  the  treaty  have  a  right  to  use  nuclear  energy 
for  peaceful  purposes. 
Again,  among  the  nuclear  powers,  China,  France,  and  India 
have  not  signed  the  treaty  along  with  many  near-nuclear  states. 
SEA-BED  ARMS  CONTROL  TREATY.   1972.   This  treaty  bans  placing 
any  nuclear  weapons  or  any  other  weapon  of  mass  destruction;  as 
well  as  structures;  launching  installations;  or  facilities  for 
storing,  testing  or  using  such  weapons  on  the  seabed,  ocean  floor 
or  in  the  subsoil  thereof  beyond  the  outer  limit  of  the  12  mile 
zone  established  by  the  Convention -on  the  Territorial  Sea  and  the 
Contiguous  Zone  of  1958. 
The  treaty  is  adhered  to  by  all  of  the  nuclear  powers  except 
China  and  France  and  has  a  total  of  55  contracting  parties. 
Each  party  to  the  treacy  has  the  right  to  ensure  compliance, 
through  observation,  of  any  other  signatory.  If  a  violation  is 
sunpected,  consultation  between  the  parties  is  held.  If  the 
situation  persists,  other  parties  must  be  notified,  and 
cooperation  for  further  verification,  including  inspection,  may 
be  agreed  upon.   If  doubt  still  remains,  the  matter  is  referred 
to  the  UN  Security  Council. 
THRESHOLD  TEST  BAN  TREATY  (TTBT) .   1974.   The  TTBT  prohibits 
underground  tests  with  yields  exceeding  IrO  KT.  A  bilateral 
agreement  between  the  US  and  USSR,  the  treaty  limits  yields  to 
less  than  150  KT  and  to  defined  test  sites. 
To  ensure  compliance  with  the  treaty  each  party  agrees  to  use 
"national  technical  means'*  of  verification  in  a  manner  consistent 
with  international  law.  They  also  agree  not  to  interfere  with
each  others'  methods  of  verification.  A  protocol  of  the  treaty 
also  specifies  "reciprocal  exchange"  of  data  to  facilitate 
verification  to  include  data  on  the  location  and  geological 
characteristics  of  the  test  areas.  Moreover,  the  yields  of  two 
explosions  in  each  geophysically  distinct  test  area  must  be 
provided  for  calibration  purposes. 
PEACEFUL  NUCLEAR  EXPLOSIONS  TREATY  (PNE) .   1976.   This  treaty 
limits  explosions  for  peaceful  purposes  to  prevent  the  use  of 
such  explosions  to  develop  new  weapons.  The  PNE  Treaty  is  a 
bilateral  agreement  that  compliments  the  TTBT.  The  provisions  of 
the  treaty  are  extensive  and  place  many  restrictions  on  any 
explosion  carried  out  at.  any  place  other  than  a  test  site. 
Simply  put,  any  explosion  having  a  yield  exceeding  150  KT  and  any 
group  explosion  with  an  aggregate  yield  exceeding  1500  KT  is 
banned.   Detailed  restrictions  described  in  the  protocol  are  put 
on  the  emplacement  o£  both  individual  and  group  explosions. 
There  is,  for  example,  a  minimum  depth  requirement  on  any 
explosion. 
'..'he  treaty  requires  extensive  bilateral  procedures  for 
verification.  The  aim  of  the  verification  measures  is 
essentially  to  ensure  that  no  individual  explosion  has  a  yield 
exceeding  150  KT.  The  treaty  is  notable  in  that  the  methods  of 
verification  required  are  tied  to  yield.  The  greater  the  yield, 
the  more  extensive  the  compliance  verification  procedures. 
Unlike  any  other  treaty,  the  parties  agree  to  on-site  inspection 
of  explosions  exceeding  150  KT.  • 
COMPREHENSIVE  TEST  BAN  TREATY  (CTBT) .   UNSIGNED.   Talks  on  a 
treaty  to  ban  all  nuclear  explosions  have  been  suspended  since 
1980.  Failure  of  the  concerned  parties  to  agree  on  methods  of 
verification,  again,  is  the  major  cause  of  the  impasse.  However, 
the  question  of  a  CTBT  is  still  under  consideration  by  the  UN 
Committee  on  Disarmament.  Characteristically,  there  is  little 
hope  of  an  early  agreement. 
The  material  presentsd  thus  far  forms  the  basis,  or  need,  for 
an  AEDS,  but  what  about  the  development  of  equipment  utilized  with 
the  AEDS.  We  know  that  equipment  development  is  necessarily 
linked  with  advances  in  nuclear  weapons  technology  and  that 
disagreement  on  methods  of  verification  have  permeated  every 
attempt  at  reaching  agreement  on  a  CTBT.  As  stated  earlier, 
concerns  about  nuclear  proliferation  have  been  expressed  since 
the  earlv  months  after  the  end  of  WWII.  These  concerns 
culmin  .tid  in  the  formation  of  the  AEDS  and  ultimately  AFTAC.  So 
much  for  the  birth  of  AFTAC,  but  how  do  we  accomplish  our 
assigned  mission.
DETECTION  CONCEPTS 
Over  the  years,  AFTAC's  operational  concepts  have  been 
continually  updated  and  refined  to  meet  the  requirements  imposed 
by  technological  advancement,   in  order  to  remain  responsive  to 
its  mission  tasking,  AFTAC  has  needed  to  improve  the  reliability 
and  capabilities  of  its  detection  systems. 
Before  discussing  the  operational  concept  of  each  system  we 
must  understand  the  phenomena  that  occur  when  a  nuclear  device  is 
exploded. 
The  Nature  of  Matter 
The  physical  universe  is  composed  of  what  is  called  matter, 
yet  it  is  difficult  to  precisely  define  matter.   It  is  customary 
to  refer  to  states  of  matter  as  solid,  liquid,  or  gas  and  say 
that  matter  has  certain  physical  properties,  such  as  color 
and/or  hardness.   All  of  this  simply  tells  us  about  matter,  not 
what  matter  is. 
Centuries  ago,  Greek  philosophers  argued  over  whether  the 
smallest  pieces  anything  could  be  divided  into  were  just 
miniatures  of  the  original  or  that  at  some  point  particles  would 
be  found  that  were  combined  in  different  ways  to  form  a  substance. 
It  is  now  known  that  the  second  argument  is  correct.   These 
independent  particles  are  called  atoms.  Therefore,  to  understand 
matter,  we  must  first  learn  about  the  atom. 
ATOMS.  All  matter  appears  essentially  electrical  in  nature. 
After  rubbing  together  pieces  of  amber  and  fur  it  is  shown  that 
both  materials  are  capable  of  picking  up  light  pieces  of  other 
material.  However,  those  attracted  by  the  amber  are  repelled  by 
the  fur  and  vice  versa.  From  this,  scientists  determined  that 
there  ere  two  types  of  electrical  charge;  positive  and  negative. 
Additionally,  like  charges  (positive  or  negative)  repel  each 
other  and  unlike  charges  attract  each  other. 
When  amber  and  fur  are  rubbed  together  particles  pass  from 
the  fur  to  the  amber,  and  the  amber  becomes  negatively  charged. 
Therefore,  the  particles  that  bring  about  this  condition  must  be 
negatively  charged. 
The  negatively  charged  particles  are  called  electrons  and  are 
fundamental  particles  of  atoms.   However,  atoms  cannot  consist  of 
electrons  alone.   If  this  were  true,  all  atoms  would  be 
negatively  charged  and  repel  each  other. 
The  positive  particles  of  an  atom  are  called  protons. 
Protons  have  greater  mass  than  electrons. 
The  final  particle  of  an  atom  is  the  neutron.  Neutrons  are 
approximately  equal  in  mass  to  a  proton,  but  unlike  the  proton 
and  electron,  they  are  not  electrically  charged.  Finally,  the 
electron,  proton  and  neutron  are  the  fundamental  particles  that 
combine  to  form  atoms  and  ultimately  matter.
ATOMIC  STRUCTURE.   Repeated  tests  have  shown  that  atoms 
contain  a  nucleus  of  protons  and  neutrons  about  v/hich  the 
electrons  orbit.   They  also  reveal  that  a  normal  atom  has  as  many 
electrons  as  it  has  protons.   The  neutrons  contribute  to  the  mass 
of  the  atom  but  do  not  effect  its  charge.   Spinning  rapidly  about 
the  nucleus,  much  like  a  shield,  the  electrons  give  size  to  the 
atom.   Figure  1  depicts  atoms  sharing  electrons  with  each  other, 
a  normal  occurrence  in  nature. 
Oxygen  Atca 
Hydrogen  Atom 
Hydrogen  Atom 
FIGURE  1  • 
MOLECULE  OF  WATER 
ELEMENTS.,  An  atom  is  the  smallest  unit  of  an  element.   Each 
element  is  a  special  combination  of  protons,  neutrons  and 
electrons.   The  distinguishing  feature  of  each  element  is  the 
number  of  protons  contained  in  its  nucleus.  Figure  2  is  a  table 
listing  the  known  elements. 
ISOTOPES.  Every  element  has  forms  that,  though  essentially 
identical  in  chemical  and  physical  properties,  have  different 
masses.   Such  forms  of  an  element  are  called  isotopes.  Each 
isotope  has  the  same  number  of  protons  in  its  nucleus  as  the 
basic  element  but  a  different  number  of  neutrons.   Hence, 
isotopes  show  differences  in  mass  when  compared  to  the  basic 
element.   For  example,  hydrogen  with  one  proton  and  no  neutrons 
in  its  nucleus  has  a  mass  number  of  1.  When  a  neutron  is 
present,  however,  the  atom  is  an  isotope  of  hydrogen,  with  a  mass 
number  of  2,  called  deuterium. 
Information  about  atomic  structure  is  expressed  symbolically 
f/ ^  subscript  number  prefixed  to  the  element's  symbol  to 
indicate  the  atomic  number  and  by  a  superscripc  indicating  the 
mass  number.   Thus  hydrogen  is  represented  by  ^h  and  the  isotope 
deuterium  H.
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COMPOUNDS.  Compounds  are  combinations  of  atoms  of  different 
elements,  Those  formed  by  life  processes  are  organic  compounds. 
All  others  are  inorganic  compounds. 
The  number  of  electrons  in  the  outer  shell  of  an  atom 
determines  the  ease  with  which  the  atom  can  join  with  other  atoms 
to  form  compounds.  Therefore,  compounds  are  formed  by  different 
atoms  gaining  or  losing  electrons.  When  two  or  more  -elements 
combine  to  form  a  compound  the  result  is  called  a  molecule.  A 
molecule  is  the  smallest  unit  of  a  compound. 
SUMMARY  ON  MATTER.  Matter  is  the  substance  of  the  physical 
universe  and  is  comprised  of  a  combination  of  atoms.  An  atom  is 
the  smallest  unit  of  an  element  and  is  seldom  found  alone  in 
nature.  They  are  found  in  combination  with  each  other  and  other 
atoms.  Atoms  of  different  elements  combine  by  exchanging  or 
sharing  electrons  to  form  compounds.  The  smallest  unit  of  a 
compound  is  a  molecule. 
Nuclear  Reactions 
There  is  a  fundamental  difference  between  a  nuclear  and 
chemical  reaction  inasmuch  as  a  nuclear  reaction  involves  the 
nuclei,  but  a  chemical  reaction  involves  only  the  electrons  of 
the  atoms.  This  means  that  in  a  chemical  process  the  elements 
are  the  same  after  the  reaction  as  they  were  before  the  reaction, 
although  they  may  appear  in  new  combinations,  whereas  in  a 
nuclear  reaction  new  elements  are  created. 
The  mass  of  a  nucleus  is  less  than  the  sum  of  the  masses  of 
the  nucleons  (protons  and  neutrons)  constituting  the  nucleus,  and 
the  mass  difference  represents  the  binding  energy  of  the  nucleus. 
According  to  Einstein's  formula,  the  mass  difference,  m, 
corresponds  to  an- equivalent  amount  of  energy,  E  *  mc2,  where  c 
is  the  velocity  of  light.  The  mass  difference,  and  thus  the 
binding  energy,  is  different  for  different  nuclei. 
There  are  basically  two  different  ways  to  release  energy  by 
a  nuclear  reaction,  either  to  split  an  element  with  many  nucleons 
say,  200,  into  elements  having  less  nucleons  but  higher  bonding 
energy  per  nucleon,  or  to  combine  elements  with  few,  say  2-6 
nucleons,  into  one  or  more  elements  having  more  nucleons  and  thus 
higher  bonding  energy  per  nucleon.  The  process  of  splitting 
"heavy"  elements  into  "light"  ones  is  called  fission,  and  the 
process  of  combining  light  elements  to  form  heavy  ones  is  called 
fusion. 
FISSION.  A  fission  explosion  is  often  called  an  atomic 
explosion,  or  A-Bomb,  like  those  dropped  at  Hiroshima  and 
Nagasaki.  The  elements  used  as  the  explosive  material  in  nuclear 
fission  devices  are  uranium  (U)  and  plutonium  (Pu) .  Two  isotopes 
of  uranium,  2^\j   and  2a~u'  with  235  and  233  nucleons'
respectively,  and  the  plutonium  isotope  g?Pu,  with  239  nucleons, 
are  used.  The  nuclear  reaction  of  the  2««U  isotope  is 
typically  written:  92 
neutron  +  giiu  2  fission  fragments  +  about  3  neutrons  + 
-  radiation  +    energy  (and  similarly  2|^U  and  g4pu) . 
This  means  that  a  uranium  or  plutonium  nucleus  captures  a 
neutron,  splits  up  into  two  fission  fragments  of  different  kinds, 
and  produces  an  average  of  three  neutrons  as  well  as  radiation 
and  energy.  A  most  important  point  is  that  the  fission  process 
generates  more  neutrons  than  it  consumes,  and  due  to  this  effect 
it  is  possible  to  create  and  sustain  a  chain  reaction.  A  minimal 
amount  of  fissile  material  is  needed  to  sustain  the  reaction,  so 
that  the  produced  neutrons  do  not  escape  from  the  process.  This 
so  called  critical  mass  depends  on  the  composition  and  geometry 
of  the  fissile  material,  presence  of  impurities,  and  on  the 
presence  or  absence  of  a  neutron  reflector,  called  a  tamper, 
surrounding  the  fissile  material  and  minimizing  the  neutron  loss. 
FUSION.   In  the  fusion  process  the  energy  is  derived  from 
forcing  together  nuclei  of  light  elements.  Two  isotopes  of 
hydrogen,  deuterium,  ?D,  and  tritium,  ?T,  are  most  commonly  used 
in  the  fusion  process.  As  isotopes  of  hydrogen,  with  the 
chemical  symbol  H,  are  used  in  the  fusion  process,  these  devices 
are  often  called  H  Bombs.  An  example  of  the  fusion  reaction  is: 
^D  +  ~r       4He  +  neutron  +  energy,  where  one  deuterium  and  one 
tritium  nucleus  are  combined  to  produce  one  helium  (He)  nucleus, 
one  neutron,  and  .a  determined  amount  of  energy.  To  start  the 
fusion  process  the  nuclei  must  be  very  close  together,  which 
means  that  they  must  have  energies  high  enough  to  overcome  the 
repelling  force  of  equally  charged  nuclei.  Such  energies  are 
achieved  by  increasing  the  temperature  to  tens  of  millions  of 
degrees,  where  the  material  consists  of  free  nuclei  and 
electrons,  plasma,  and  the  nuclei  have  enough  thermal  energy  to 
start  a  fusion  reaction.  A  reaction  based  on  the  thermal  energy 
of  the  nuclei  is  often  called  a  thermonuclear  reaction.  To 
sustain  a  thermonuclear  reaction,  the  energy  produced  must  be 
larger  than  that  radiated  from  the  process;  otherwise  the 
temperature  decreases  and  the  reaction  stops. 
Bomb  designs. 
A  fission  device  requires  two  components.  The  first  is  a 
subcritical  mass  arranged  in  such  a  way  that  it  can  almost 
simultaneously  be  made  supercritical.  The  second  is  a  strong
neutron  source  to  initiate  the  reaction.   There  are  two  ways  to 
construct  such  a  device. 
GUN  METHOD.   In  the  gun  method  two  or  more  pieces  of  fissile 
material,  each  of  subcritical  size,  are  brought  together  by 
conventional  explosives  to  form  a  supercritical  system,  where 
upon  the  chain  reaction  is  initiated  by  a  neutron  source.   Refer 
to  Figure  3. 
£ 
Suberlties! 
mas* 
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t 
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Supercritical  mess  -i 
{Immediately  after  firing) 
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Figure  3 
GUN  METHOD 
IMPLOSION  METHOD.  With  the  implosion  method,  the  nuclear 
material  is  in  the  form  of  a  subcritical  shell,  which,  at  the 
explosion  moment,  is  compresses  by  conventional  high  explosives 
to  a  compact  .supercritical  mass  and  the  chain  reaction  is 
initiated.   Figure  4  depicts  this  construction  method. 
Subcritical  mass-i 
Compressed  supercritical  miss— 
Implosion 
Chemical  cip!cs!v3 
(3efore  firing) 
[immediately  after  firing) 
Tt  :n  explodes 
Figure  4 
IMPLOSION  METHOD
The  principle  construction  of  nuclear  fusion  devices  is  not 
generally  known  in  as  much  detail  as  that  of  fission  devices. 
Presently,  it  appears  that  only  a  fission  explosion  is  capable  of 
producing  the  temperatures  necessary  for  a  thermonuclear  reaction 
to  start,  and  trigger  fusion. 
A  fusion  bomb  with  a  fission  part  contributing  only  a  few 
percent  of  the  total  yield  seems  possible.  The  possibility  of 
initiating  a  fusion  explosion  by  means  other  than  a  fission 
reaction,  for  example  high  energy  laser  radiation,  and  thus  to 
obtain  a  pure  fusion  explosion  have  been  discussed,  but  no 
substantial  progress  has  been  reported. 
Nuclear  Explosion  Phenomena. 
For  a  chemical  (TNT)  explosion  the  detonation  velocity  is 
about  6000  m/s  which  means  that  a  1  Kt  sphere  with  a  radius  of  5.5 
m  detonates  within  a  billisecond.  The  produced  explosion  gasses 
have  an  initial  pressure  of  about  200,000  atmospheres  and  a 
maximum  temperature  of  3000°K.  Almost  all  of  the  energy  released 
in  a  chemical  explosion  is  converted  to  shock-wave  energy.   In  a 
nuclear  explosion  the  energy  is  produced  within  a  very  short 
time,  less  than  a  microsecond.   Immediately  after  the  explosion 
the  energy  is  deposited  within  a  small  volume  of  hot  and  compressed 
gas.  In  a  fission  explosion  the  initial  gas  temperature  amounts 
to  tens  of  millions  of  degrees  Kelvin  and  the  pressure  exceeds  a 
million  atmospheres.  The  hot  gas  emits  electromagnetic  radiation 
in  the  form  of  X-rays.  This  radiation  is  absorbed  very  rapidly 
and  heats  the  surrounding  media,  so  at  this  stage  the  energy 
propagates  outward  as  thermal  radiation.  The  heated  material 
also  compresses  the  surrounding  media,  and  a  very  hot  shock  wave 
results.  For  an  explosion  in  the  atmosphere,  50%  of  the 
explosion  energy  is  converted  to  blast  and  shock  wave  energy,  35% 
to  thermal  radiation,  and  the  remaining  15%  is  initial  and 
residual  radiation. 
In  an  underground  nuclear  explosion,  the  thermal  radiation  is 
absorbed  by  the  surrounding  dense  material.  Therefore,  the 
sphere  of  action  is  much  smaller  than  that  of  an  atmospheric  one. 
The  close-in  explosion  phenomena  for  a  fully  contained 
underground  explosion  are  illustrated  in  Figure  5.  The  intense 
shock  wave  of  high  temperature  melts  or  vaporizes  the  material  in 
the  immediate  vicinity  of  the  explosion  and  forms  an 
approximately  spherical  cavity.  Outside  the  cavity,  inelastic 
deformation  and" cracking  of  the  rock  occur  up  to  a  certain 
distance  beyond  which  the  material  acts  elastically.  Analysis 
indicates  that  90  to  95%  of  the  released  explosion  energy  is 
deposited  as  thermal  energy  in  the  vicinity  of  the  explosion.
SCO     TIME  {mil 
Figure   5 
CLOSE-IN   EXPLOSION   PHENOMENA 
In  studies  of   seismic  waves  generated  by  underground   nuclear 
exolosions,    the  detailed  behavior  of  the   inelastic  zone  are  not 
considered.     The  seismic  source  of  an  underground  explosion  is 
usually  considered  an  elastic  sphere  having  a  radius  equal  to  the 
distance  from. the  explosion  Foint   to  where   the  material  begins  to 
act  elastic.  fi   ..      *.«*•*  i 
Finally,    for   an 'explosion  underwater,   up  to   40%  of   the   total 
energv  produced   is  in  the   form  of   a  shock  wave. 
OPERATIONAL  CONCEPTS 
In  the  past  AFTAC  has   utilized  many  systems   to  detect   the 
phenomena  resulting   from  the  detonation  of   a  nuclear  aevice: 
^evc-ral  of   these  were   the   result  of   researc.i  ana  cevelopmen. 
projects,    and  due   to   technological  advances  have  been  modernized, 
deleted,   or   replaced. 
In  o-der  to  coerate  and  maintain  the  AEDS,   AFTAC  manages 
locations    in  more" than  thirty  five  countries.     The  headquarters 
is    loc  =  t«d    at   Patrick   APS,    Florida,  „ith  the  Technical. .Operations  Division 
at  McClellen  AFB,   California  and  operating,  areas  at  Wheeler  AFB,   Hawaii  and  Lindsey 
AS,   Germany.   There  are  nineteen  detachments    (Dets) ,   four  operating  locations (OLs) 
and  more  than  fifty  equipment"  locations   (ELs)  around  the  globe. 
IS
The  operating  areasin  Hawaii  and  Germany  provide  administrative 
and  logistic  support  to  subordinate  units  within  their 
geographical  areas  of  responsibility.  The  ...Top   ^  located  at 
McClellan  supports  three  separate  activities,"  the  Central 
Laboratory,  the  Logistics  Depot,  and  the  Airborne  System. 
McClellan  Central  Laboratory 
The  Central  Laboratory  (MCL)  is  a  scientific  facility 
utilizing  modern  analytical  equipment  in  support  of  the  AEDS 
mission.   Approximately  100  different  techniques  are  employed  to 
accomplish  this  task.  Aside  from  managerial  and  support  offices, 
the  MCL  is  divided  into  three-  separate  laboratories. 
APPLIED  PHYSICS  LABORATORY.   This  section  of  the  MCL  is 
responsible  for  sample  preparation,  optical  characterization, 
instrumental  analysis,  identification  of  samples,  and  precision 
isotopic  measurements  of  samples.  Additionally,  it  assists  in 
the  evaluation  of  data  derived  from  other  analysis  techniques  and 
conducts  research  and  development  to  improve  the  quality  of 
analysis. 
RADIATION  ANALYSIS  LA30RAT0RY.   This  section  is  responsible 
for  managing  the  flow  of  samples  through  chemical  processing 
techniques  involving  dissolution,  separation,  purification,  and 
instrumental  analysis.  Measurement  of  chemically  separated 
radioactive  samples  using  alpha,  beta,  and  gamma  detection 
systems  is  also  accomplished  here.  Moreover,  this  section 
performs  measurement  of  radioactive  samples  in  the  form  of  filter 
papers,  solutions,  gas  samples,  and  other  "as  received"  samples. 
G7.S  ANALYSIS  LABORATORY.  This  laboratory  performs 
separation,  purification  and  measurement  of  all  radioactive 
gasses  of  interest  to  AFTAC. 
LOGISTICS  DEPOT.  Because  the  unique  systems  and 
instrumentation  are  only  applicable  to  the  AEDS  mission,  th^ 
depot  distributes  items  managed  by  AFTAC.  Additionally,  the 
depot  prepositions  assets  for  AEDS  systems,  provides  parts 
support  for  depot  level  maintenance,  and  provides  normal  base 
level  support. 
The  dets,  ELs,  and  OLs  facilitate  mission  accomplishment  by 
providing  operational  environments  for  placement  and 
implementation  of  equipment  utilized  by  AFTAC.  The  mission 
requirement  to  detect  debris  in  all  mediums  results  in  the 
employment  of  many  diverse  techniques.
Airborne  Systems 
AFTAC  utilizes  airborne  particulate  and  gas  sampling  devices 
to  c'onFirm,  and  subsequently  track, "clouds,  of  nuclear  debris. 
Filtering  devices  and  pressurized  spheresjnounted  aboard  modified 
aTrcraf t  collect  samples  tnat  are  rorwarded  to  MCL  for  analysis 
and  classification.  ~ 
Ground  Based  Systems 
There  are  three  ground  based  systems  that  provide  samples  to 
the  MCL  for  analysis  and  classification. 
GROUND  FILTER  UNIT  (GFU) .   The  GFU  is  an  electrically 
powered,  ground  based,  air  filtering  unit.   It  is  designed  for 
continuous  operation,  employing  an  electric  motor  coupled  to  a 
blower  assembly.   Free  air  is  drawn  into  a  transition  cone,  flows 
through  a  filter  element  (paper) ,  and  is  then  exhausted  to  the 
atmosphere.  The  filter  paper  containing  airborne  particles 
collected  from  the  atmosphere,  is  then  removed  and  forwarded  to 
the  MCL  for  analysis  and  classification. 
GROUND  MOISTURE  UNIT  (GMU) .   The  GMU  is  a  ground  based,  whole 
air  sampling  device.  Two  glass  traps  are  employed  in  the  unit. 
The  first  contains  a  molecular  sieve  that  removes  water  va::or 
from  free  air.   The  second  trap  contains  a  molecular  sieve  coated 
with  palladium.   The  palladium  acts  as  a  catalyst  to  oxidize 
gaseous  hydrogen  and  form  water  vapor  that  is  absorbed.   The  unit 
is  designed  to  operate  continuously.  The  traps  are  changed  daily 
and  forwarded  to  MCL  for  analysis  and  classification. 
B20-5.  The  B20-5  is  an  automated  cryogenic  distillation 
device  that  emoloys  very  low  temperatures  to  isolate  rare_ 
elements  (gasses)  contained  in  the  atmosphere.   The  unit  is 
designed  to  operate  continuously  over  any  preset  sample  run  of  24 
hours  (or  multiples  thereof)  for  periods  of  up  to  seven  days. 
Samples  are  collected  in  800  cc  metal  containers  that  are 
forwarded  to  the  MCL  for  analysis  and  classification. 
Seismic  System 
The  seismic  system  consists  of  a  global  network  of  manned 
stations  that  report  concise  seismological  data  to  a  central 
analysis  terminal  located  within  the  headquarters.  Each  station, 
or  det,  possesses  broadband  seismic  detection  capabilities. 
Oo»rated  on  a  24  hour  a  day  basis,  each  det  must  detect,  record, 
and  analyze  all  of  the  seismic  activity  that  occurs.  The  result 
of  this  process  is  transmitted  to  headquarters  where  a 
determination  of  the  generation  mechanism,  or  source,  is  made.
GLOBAL  SEISMIC  OPERATIONS,  CENTER, (GSOC) ...  Known  as  the  B  Data  _ 
rminal  (BDT)  or  "Zip  Room",  the  gsoc  is  responsible 
Terminal  (BDT)  or  "Zip  Room",  the  gsoc  is  responsible  for  both 
real-time  analysis  and  delayed  data  processing.   Data  from  North 
American  seismic  network  stations  is  received  directly  from  the 
field  via  hign-"spee~d  communications  circuits,  and  is  recorded  on 
fTlm  for  analysis.   Data  from  the  remaining  network  stationjsjjnrd 
"the  National  Earthquake  Information  Center  (NZIC) ,  is  analyzed 
using  tne  Automatic  Data  Association  and  Processing  System 
(ADAPS) .  This  system  Is  covered  completely  in  a  subsequent  block 
of  instruction. 
Hydroacoustic  System. 
The  Hydroacoustic  system  consists  of  a  worldwide  network  of 
ELs  €h~at  transmit/  m  digital  £orm,  recorded  hydroacoustic  data 
(sound  waves  in  water)  to  a  central  analysis  terminal  located" 
within  the  headquarters.   Operated  on  a  24  hour  a  day  Dasis ,  the 
hydroacoustic  data  terminal  is  tasked  to  identify  the  source  of 
each  recorded  wave. 
The  Hydroacoustic,  or  Digital  "0"  System  (DOS) ,  is  comprised 
of  two  separate  systems  that  are~~inter  related;  the  Acquisition 
and  Analysis  Systems .   The  Acquisition  System  presently  consist s 
of  up  to  9  "0"  Field  Sets  (OFS).  The  Analysis  System  is  more 
conLmonTy~ref  erred  to"  as  the"HydYc-acoustic  Recorder  and  Processor 
(HRP1.  - 
The  OFS  is  a  real  time  data  acquisition  system  designed  to 
collect  raw  data,  perform  frequency  filtering,  data  processing* 
message  formatting,  and  data  transmission. 
The  Analysis  System  of  the  DOS  is  comprised  of  the  HRP.  The 
primary  purpose  of  the  HRP  is  to  collect  and  process  data  from 
the  OFSs.   In  order  to  accomplish  these  tasks,  it  is  divided  into 
two  functional  hardware  subsystems.  The  primary  subsystem  provi- 
des data  collection,  recording,  display,  analysis,  and  com- 
munication with  each  OFS.  The  secondary  subsystem  serves  as  back 
up  for  the  primary  in  case  of  failure,  at  which  time  it  automati- 
cally assumes  the  primary  system  tasks. 
Electromagnetic  Pulse  System  (EMP) . 
The  EMP  system  consists  of  a  worldwide  network  of  detachments 
used  for  detecting,  locating,  and  Identifying  the  source  of^  the 
Electromagnetic  Pulse  signals  occurring  inThe  atmosphere":  ~Tht s 
:em  is  comprised  of  J  Field  Sets  (JFS)  that  are"lln<ed,  via 
dedicated  lines  to  the  Central  Data  Terminal  (CDT)  located  wtthin 
the  headquarters";  '      " 
The  EMP  system  is  a  continuously  operating  electronic 
technique  having  the  capability  to  detect,  process,  and  record
randomly  occurring  electromagnetic  pulses  in  the  Very  Low 
Frequency  (VLF)  and  High  Frequency  (HF)  spectra. 
Data  from  EM?  signals  that  satisfies  priority  criterion  at 
the  JFS  is  transmitted  in  real  time  to  the  CDT  via  a  synchronous 
communication  circuit. 
The  CDT  is  a  continuously  operating  computer  terminal  having 
the  capability  to  receive  EMP  signal  descriptor  data_  from  all  JFS 
sites  via  dedicated  communications  lines  and  to  perform  real  time 
data  processing  of  the  incoming  data. 
The  CDT  also  functions  as  the  central  technical  control  faci- 
lity for  all  EMP  Technique  operations  and  functions.  These 
operations  and  functions  includes  providing  output  reports;  main- 
taining historical  data  files;  reporting  the  CDT  and  JFS  status; 
performing  housekeeping  functions;  and  adjusting  the  operating 
parameters  at  all  JFS  sites. 
MISSION  CONTRIBUTIONS 
The  contribution  of  each  of  the  aforementioned  systems  is 
indispensable  to  mission  accomplishment.  Although  the  systems 
are  designed/  for  the  most  part,  to  monitor  within  a  specified 
media  their  applications  often  overlap. 
As  stated,  the  airborne  systems  utilize  particulate  and  gas 
sampling  devices  to  confirm,  and  subsequently  track,  clouds  of 
nuclear  debris.  Of  course,  the  debris  results  from  the 
detonation  of  a  nuclear  device,  however,  the  test  need  not  occur 
in  the  atmosphere.   Venting  from  underground  or  underwater  tests 
may  result  in  the  formation  of  such  clouds.  Therefore,  the 
system  can  substantiate  preliminary  determinations  based  on  data 
collected  by  both  the  seismic  and  hydroacoustic  systems. 
The  seismic  system  is  designed  to  detect  minute  amounts  of 
ground  movement.   When  an  earthquake  occurs,  waves  are  generated 
that  propagate  away  from  the  source.   In  order  to  propagate  the 
waves  must  cause  particle  motion,  or  ground  movement,  that  can  be 
detected.   An  underground  explosion  results  in  the  same  waves 
being  generated,  however  discrimination  techniques  are  applied  to 
determine  their  true  source.   By  utilizing  these  methods  of 
discrimination,  AFTAC  is  capable  of  monitoring  underground 
explosions. 
The  detonation  of  an  explosive  device  underwater  produces
sound  waves  that  ate  recorded  with  specific  envelopes,  or 
characteristic  appearances.  The  observation  of  this  type  of  wave 
is  the  only  initial  indicator  that  an  underwater  test  has 
occurred. 
The  primary  mission  of  the  Hydroacoustic  Technique  is  to 
supplement  the  Seismic  Technique  in  detecting,  locating,  and 
identifying  underwater  explosions.   A  secondary  mission  is  to 
detect,  locate,  and  identify  other  underwater  phenomena  that  may 
be  of  military  significance.
EXERCISE  1 
Procedure: 
Complete  or  respond  to  the  following: 
1.  The  first  nuclear  weapons  test  was  conducted  on 
  . 
  at 
2.   Name  the  individual  placed  in  charge  of  the  USSR' 
version  of  the  "Manhattan  Project". 
3.  The  Acheson-Lilienthal  report  was  presented  to  the  UN  as 
the 
4.  The  yield  of  underground  nuclear  weapon  tests  is  limited 
to  150  KT  by  the    . 
5.  A  fission  explosion  is  often  called  a/an 
6.  Name  the  three  laboratories  housed  within  the  MCL.
7.  The  GMU  utilizes  a  glass  trap  containing  a  molecular 
sieve  coated  with 
8.   Name  the  two  separate  systems  that  comprise'  the  DOS.
Instruction  Section 
Lowry  Air  Force  Base,  Colorado 
SW  G3A8R99105-000-V-3 
-A8 .9?tpber  1984 
GEOGNOSY 
OBJECTIVES 
o   Given  five  definitions  of  terms  used  in  geology,  select 
the  definition  of  geognosy. 
o   Given  an  illustration  of  the  Earth,  label  the  major 
layers. 
o   Given  an  illustration  of  the  ocean,  label  the  major 
layers. 
o   Given  an  illustration  of  the  atmosphere,  label  the  major 
layers. 
o       Match  each  of  four  terms  to  a  statement (s)  describing  the 
Geographic  Grid  Coordinate  System. 
INTRODUCTION 
The  study  of  Earth  and  its  components  (land,  ocean  and 
atmosphere)  is  a  complicated,  yet  interesting  endeavor.   It  often 
begins  with  a  presentation  of  theories  concerning  Earth* s 
formation  and  concludes  with  speculation  about  the  universe, 
invariably  leaving  the  most  ardent  student  confused  and  dismayed. 
This  unit  is  designed  to  avoid  these  undesirable  aspects.   It 
acts  as  an  introduction  to  Geognosy,  or  "the  branch" of  geology 
that  deals  with  the  constituent  parts  of  the  earth,  its 
atmosphere  and  water,  its  crust,  and  the  condition  of  its 
interior". 
The  key  words  in  the  previous  paragraph  are  "theories"  and 
"speculation".  You  must  realize  that  in  the  study  of  Geognosv 
many  conclusions  are  based  upon  indirect  observation.  Few  facts 
about  the  Earth,  its  oceans  and  atmosphere  are  determined  first 
hand.  Man  has  yet  to  devise  methods  of  directly  probing  the 
interior  of  Earth,  the  depths  of  the  oceans,  and  heights  of  the 
atmosphere,  however,  excellent  and  widely  accepted  models  of  each 
do  exist  and  are  continually  being  refined  as  technology  advances. 
The  following  information  presents  simplistic  descriptions  of 
each  area  covered  in  geognosy  and  forms  the  basis  for  more  in 
depth  study  at  a  later  point. 
INFORMATION
EARTH  STRUCTURE 
The  study  of  the  Earth  is  likened  to  observing  an  egg.  The 
outward  appearance,  texture,  temperature  and  composition  ace 
easily  discerned,  however,  little  is  known  of  its  interior  from 
this  form  of  observation.  Breaking  the  egg  remedies  this 
dilemma,  but  another  method  is  required  to  investigate  Earth's 
interior  (i.e.,  a  method  of  indirect  observation). 
Our  knowledge  of  the  Earth's  interior  is  based,  primarily,  on 
the  observation  of  seismic  waves.  When  a  seismic  disturbance, 
either  a  natural  earthquake  or  an  underground  explosion,  occurs, 
waves  are  generated  that  display  certain  characteristics.   The 
velocity,  or  speed  of  travel,  of  these  waves  in  different 
materials  is  known  from  laboratory  experiment.  So,  if  an 
earthquake  occurs  at  a  known  time  and  distance  from  a  recording 
station  scientists  can  determine  the  types  of  materials  existing 
between  the  two  points.   Moreover,  as  seismic  waves  propagate 
they  change  direction,  revealing  several  places  within  the  Earth 
where  changes  occur  in  the  physical  properties  of  the  materials. 
These  changes  could  result  from  differences  in  composition, 
atomic  structure,  or  atomic  stzte.  The  boundary  where  such 
changes  take  place  is  called  a  discontinuity. 
On  the  basis  of  data  assembled  from  studies  of  the  travel 
habits  of  seismic  waves  the  earth  has  been  divided  into  three 
major  zones;  crust,  mantle,  and  core. 
Crust. 
It  has  been  difficult  to  gather  precise  data  on  the  Earth's 
crust  from  seismic  waves  originating  from  earthquakes.  Waves 
from  explosions,  however,  with  accurate  location  and  origin 
times,  have  filled  in  most  of  the  details. 
The  average  velocity  of  waves  travelling  in  the  upper  region 
of  the  crust  are  similar  to  the  velocity  expected  for  granite, 
granidiorite,  or  gneiss.   Because  these  rocks  are  rich  in  silica 
and  aluminum  we  say  the  material  of  the  upper  crust  is  sialic  in 
composition;  the  term  SIAL,  SI  for  silicon  and  AL  for  aluminum, 
is  generally  used  when  speaking  of  this  layer.   This  layer  is  only 
found  in  the  continental  regions  of  the  earth  and  is  sometimes 
referred  to  as  Continental  Crust. 
A  second,  more  basic  layer  encircles  the  entire  Earth.  Waves 
travelling  in  this  region  display  velocities  similar  to  those 
expected  of  a  wave  travelling  through  basalt.  This  darker, 
heavier  rock  is  designated  SIMA;  SI  for  silicon  and  MA  for 
magnesium.   This  layer  is  the  outermost  rock  layer  under 
permanent  ocean  basins  and  is  sometimes  referred  to  as  Oceanic 
Crust. 
It  is  obvious  that  SIAL  is  not  present  in  all  areas.   This 
fact  accounts  for  differences  in  the  thickness,  or  depth,  of  the
crust.  SIMA  reaches  to  depths  of  only  5  to  15  km  in  the  ocean 
basins,  while  extending  up  to  100  km  deep  in  continental  areas. 
The  weight  of  the  overlying  SIAL,  or  continental  crust,  causes 
the  SIMA  to  "sink"  deeper  into  the  next  region. 
Mantle. 
Below  the  Earth's  crust  is  the  second  major  zone,  the  mantle, 
which  extends  to  a  depth  of  2900  km. 
Below  the  discontinuity  formed  by  the  bottom  of  the  crust  and 
top  of  the  mantle  seismic  wave  velocity  increases  drastically. 
This  indicates  that  the  composition  of  the  material  suddenly 
changes.  We  have  no  direct  evidence  of  the  new  material's 
nature,  but  the  change  in  speed  suggests  that  it  may  contain  more 
ferromagnesian  minerals  than  the  drust.  For  many  years,  most 
scientists  have  agreed  that  the  mantle  is  solid  in  nature  but 
suspect  that  it  may  be  capable  of  flow.  This  fact  appears  reaso- 
nable at  least  for  the  upper  portion  (the  asthenosphere  at  200 
km)  of  the  mantle.   In  this  region,  there  are  distinct  effects  on 
the  velocity  of  certain  seismic  waves. 
What  produces  this  change  in  the  mantle?  It  may  be  a 
rearrangement  of  atoms  under  pressure  or  a  change  in  the  kinds  of 
atoms.  We  do  not  know  exactly,  yet.  Whatever  the  new  material 
or  state  of  matter  that  produces. the  change,  the  mantle  seems 
substantially  uniform  from  600  down  to  2900  km. 
Core. 
We  come  now  to  the  core,  a  zone  that  extends  from  the  bottom 
of  the  mantle,  at  2900  km,  to  the  center  of  the  earth  at  6370  km. 
Variations  in  the  observation  of  seismic  waves  suggest  that  the 
core  is  really  a  liquid  layer  2255  km  thick,  surrounding  a  very 
dense,  solid,  central  sphere  1215  km  in  radius.   Designated  the 
outer  core  and  inner  core,  respectively,  these  areas  are  believed 
to  constitute  30%  of  the  Earth's  mass. 
More  in  depth  information  about  the  structure  of  the  Earth's 
interior  is  presented  in  subsequent  blocks  of  instruction. 
Figure  6,  however,  summarizes  the  information  presented  thus  far. 
OCEAN  STRUCTURE 
The  layers  of  the  ocean  are  not  as  clearly  defined  as  that  of 
the  Earth.  This  is  due,  in  part,  to  the  relative  ease  of  its 
observation  and  the  particular  interest  of  those  conducting  the 
study.  Biologists  determine  layers  by  the  type  of  animal  life 
present  at  different  depths.  Oceanographers  often  classify  by 
differences  in  temperature.   Individuals  interested  in 
hydroac rustics,  or  the  propagation  of  underwater  soundwaves, 
outline  layers  based  on  differences  in  the  speed  of  these  waves 
in  water.
SIMA 
Figure  6 
STRUCTURE  OF  THE  EARTH 
The  speed  of  a  hydroacoustic  wave  is  determined,  primarily, 
by,  the  temperature  of  the  water  and  pressure.   Each  of  these 
faccors  vary  with  depth.   Temperature  decreases  linearly  with 
depth  until  a  minimum  of  3  -  4°C  is  reached  and  the  speed  of 
sound  waves  in  water  decreases  drastically  with  decreasing 
temperature.  Of  course,  pressure  is  proportional  to  depth  and 
souni  wave  velocity  increases  with  increasing  pressure.   The 
interaction  of  the  two  forces  creates  the  interesting  graph 
depicted  in  Figure  7. 
VELOCITY 
Fiaure  7 
INTERACTION  OF  PRESSURE  AND  SOUND  VELOCITY
It  is  apparent  that  the  slowing  effect  of  decreasing 
temperature  outweighs  the  change  in  speed  (increase)  resulting 
from  increased  pressure.  These  combined  influences  form  the 
basis  of  hydroacoustic  layering. 
Thermocline. 
The  main  thermocline  is  the  area  in  which  sound  wave  speed 
decreases  drastically  with  decreasing  temperature.  The  depth,  or 
thickness,  of  the  main  thermocline  is  influenced  by  many  things 
including  external  mean  temperature,  seasonal  temperature 
variations,  currents,  and  location  in  respect  to  the  equator. 
The  temperature  constant  is  reached  at  a  depth  of  5000  feet  in 
equatorial  waters  (mean  temperature  82°F)  as  opposed  to  very 
near,  or  at  the  surface,  in  polar  regions  (mean  temperature 
30°F) .  The  seasonal  variation  of  external  temperature  in  both 
regions  accounts  for  migration  of  up  to  100  feet  of  the  tem- 
perature constant.  Additionally,  the  cold  currents  prevalent  in 
the  Pacific  Ocean  cause  the  constant  to  present  itself  at  3500 
feet,  while  the  warm  currents  of  the  Atlantic  delay  this  to 
depths  of  up  to  5000  feet. 
Sound  Channel  Axis. 
The  sound  channel  axis  describes  the  area  of  minimum  sound 
wave  speed.  This  region  results  from  the  interaction  of  the 
effects  of  temperature  and  pressure  variations  and  facilitates 
the  propagation  of  small  amounts  of  sound  over  long  distances. 
In  their  book,  Elastic  Waves  in  Layered  Media,  W.  Lwing,  W. 
Jardetzky,  and  P.  Press,  (McGraw  -  Hill  Book  Co.  Inc.,  New  York, 
1957,  page -337)  describe  the  propagation  capability  of  the  sound 
axis  in  the  following  manner:   "the  extremely  long  range 
transmission  of  sound  (probably  10,000  miles  for  small  bombs)". 
Deep  Isothermal  Layer. 
This  layer  exists  below  the  sound  channel  and  extends  to  the 
ocean  bottom.   It  is  marked  by  constant  temperatures,  relatively 
high  levels  of  salinity,  and  linear  velocity  increases  with 
increasing  pressure. 
ATMOSPHERIC  LAYERS 
The  atmosphere  of  the  Earth  is  divided  into  five  layers  and 
one  intermediate  region  of  great  importance  to  the  99105.  The 
existence  of  these  layers  and  their  importance  are  often  taken 
for  granted,  if  not  ignored.  The  atmosphere  exists  as  a  result 
of  the  gravitational  force  of  the  Earth  and  the  layers  are 
defined  by  variations  in  temperature  and  molecular  abundances. 
Figure  8  depicts  these  layers.
EXOSPHERE 
THERMOSPHERE 
STRATOSPHERE 
TROPOSPHERE 
Figure  8 
ATMOSPHERIC  LAYERS 
Troposphere 
The  troposohere  is  the  first  of  the  layers ,  and  the  one  man 
is  most  familiar  with.   Extending  to  heights  of  approximately  8 
lea  near  the  poles  and  17  km  near  the  equator,  this  layer  is  the 
center  of  all  weather  sources.   Solar -radiation  and  thermal 
heating  produce  convection  currents  resulting  in  winds  that  range 
from  gentle  breezes  to  dangerous  hurricane  force.   The  presence 
of  dust  particles  and  the  high  water  vapor  content  of  this  region 
produce  clouds  and  rain.   These  factors  lead  to  the  conclusion 
that  with  the  exceoticn  of  mild  turbulence  in  the  lower  region  of 
the  next  laver,  the  troposphere  is  the  only  "active"  region.  The 
troocsohere'is  distinguished  in  two  other  v/ays.   First,  it  is  the 
only  laver  that  displays  a  steady  decrease  in  temperature  with 
increasing. elevation.  This  drop,  averaging  3*°F  for  each  1000 
feet,  is  referred  to  as  "lapse  rate".   In  the  layers  above  the 
trooosohere  the  laose  rate  is  either  positive  or  negative 
depending  on  the  layer.  Secondly,  the  troposphere  is  by  far  the 
most  dense  layer  comprising  the  largest  percentage  of  the  mass  of 
the  atmosphere. 
Stratosphere 
The  stratosphere  extends  from  the  outer  limit  of  the 
trooosohere  (8-17  km)  to  a  maximum  height  of  approximately  50 
km."  This  is  a  fairly 'stable  layer  with  little,  if  any,  influence 
on  weather.  The  temperature  of  this  region  is  determined  by. 
solar  radiation  and  its  w?.ter  vapor  content  is  low  compared  to 
the  trooosphere.   The  presence  of  an  ozone  layer  near  its  upper 
limit  is  of  utmost  imcortance  because  it  absorbs  excess  amounts 
o*   harmful  ultraviolet  solar  radiation.  The  ozone  layer  thus
possesses  a  negative  lapse  rate.  Temperatures  measured 
simultaneously  above  and  below  the  ozone  layer  ace  recorded  as 
low  as.  -100°F  while  the  temperature  of  the  layer  itself  may  range 
to  30°F  or  40°F. 
Mesosphere 
The  mesosphere  borders  the  stratosphere  and  extends  to  a  maximum 
height  of  about  80  km.   IN  this  layer,  temperature  again 
decreases  with  altitude  to  about  -110*?.  The  major  importance  of 
this  layer  is  that  it  contains  the  lower  portion  of  the  inter- 
mediate region  called  the  ionosphere. 
Thermosphere 
Bordering  the  mesosphere  and  climbing  to  an  altitude  of  about 
600  km  is  the  largest  of  the  layers;  the  thermosphere.  The  tem- 
perature in  this,  layer  again  increases  with  altitude  and  is 
greatly  affected  by  solar  activity  and  time  of  day.  The 
remainder  of  the  ionosphere  from  80-40Q  km  also  falls  in  this 
layer  and  is  of  prime  interest  to  us. 
Ionosphere 
The  ionosphere  extends  from  about  60  km  to  a  maximum  height 
of  400  km.  As  mentioned  earlier,  this  area  occupies  a  position 
in  both  the  mesosphere  and  thermosphere.   It  is  unique  in  that  it 
contains  bands  of  ionized  air  that  reflect  radio  waves,  including 
those  that  result  from  nuclear  explosions.  These  bands  of 
inoization  have  been  given  the  letter  designations  D,  E,  Fl,  F2, 
and  F,  depending  upon  their  location  in  either  day  or  night. 
Exosphere . 
The  exosphere  extends  above  the  thermosphere  and  is  a  tran- 
sition zone  between  the  atmosphere  and  space.  Although  this  area 
is  extremely  rarefied,  traces  of  the  Earth's  atmosphere  are  still 
found.  This  indicates  that  the  boundary  between  space  and  the 
atmosphere  is  not  well  defined. 
GEOGRAPHIC  GRID  COORDINATE  SYSTEM 
The  geographic  grid  coordinate  system  is  merely  a  method  of 
precisely  locating  a  point  on  the  Earth's  surface.  Each  point  is 
defined  by  assigning  degrees  of  longitude  and  latitude.  Refer  to 
Figure  9  while  reading  the  following  information.
KE?.IDIASS 
PARALLELS 
GRID 
Figure   9 
GEOGRAPHIC   GRID   COORDINATE   SYSTEM 
Grid 
The  term  grid  defines  the  network  of  lines  of  longitude  and 
latitude  used  on  a  map  or  globe. 
Longitude 
The  term  longitude  defines  the  grids  running  north  and  south 
and  converging  at  the  poles.   Also  referred  to  as  meridians, 
lir.es  of  longitude  each  scribe  one  half  of  a  great  circle,  or  the 
longest  direct  path  around  the  Earth.   They  are  used  to  measure 
distances  of  up  to  180°  east  and  west  of  the  prime  meridian 
(0°  longitude).   The  prime  meridian,  by  international  agreement, 
is  the  line  of  longitude  extending  from  pole  to  pole,  and  passing 
through  Greenvich  England,  the  former  site  of  the  Royal 
Observatory. 
Latitude 
The  term  latitude  defines  the  grids  running  east  and  west  and 
parallel  to  the  equator  (0°  latitude).  Also  referred  to  as 
parallels,  lines  of  latitude  are  used  to  measure  distances  of 
up  to  90°  north  and  south  of  the  equator.  The  equator  is  the 
only  grid  that  scribes  a  true  great  circle,  or  line  which  if 
extended  to  a  plane  would  bisect  the  Earth.   Each  of  the  other 
parallels  decrease  progressively  in  circumference  as  they  move 
away  from  0°. 
Degree 
As  a  matter  of  convention  the  Earth  is  considered  a  sphere. 
Thus,  one  degree  is  equal  to  the  Earth's  circumference  (24,900 
mi)  divided  by  360°.  This  distance  is  expressed  as: 
24,900  mi 
69  statute  miles  (approximately)
4360Q5  km  =  U1  kiloraeters  (approximately) 
It  is  important  to  note  that  the  lines  of  longitude  do 
converge  and  the  distance  of  1°  of  longitude  is  reduced  to 
approximately  one  half  or  34*  miles  (55i  km)  at  60°  north  and 
south.  . 
Each  degree  is  further  divided  into  minutes  and  seconds. 
MINUTE.   Each  minute  is  equal  to  one  sixtieth  of  a  degree. 
Therefore/  this  number  is  expressed  as: 
69  mi  -  Lis  statute  miles  (aDproximately ) 
or 
111  km  =1.85  kilometers  (approximately) 
SECOND.  Each  second  is  equal  to  one  sixtieth  of  a  minute. 
Therefore,  this  number  is  expressed  as: 
1.15  mi  =  .02  statute  miles  (approximately) 
or 
1.85  km  s  .03  kilometers  (approximately) 
« 
Location. 
Locating  a  point  on  the  Earth's  surface  becomes  an  easy  task 
when  III   geographic  grid  coordinate  system  i, j  used.  For  example, 
the  coordinates  of  Boulder,  Wyoming  are  46°  34'  02  N  by  109°  34 
57"  W.   These  coordinates,  read  46  degrees,  34  minutes,  2  seconds 
north  bv  109  degrees,  34  minutes,  and  57  seconds  west,  reveal  the 
approximate  location  of  this  small. town  with  just  J  cursory 
glance  at  a  globe.   (Note  that  latitude  is  always  stated  first).
EXERCISE  2 
Procedure: 
Complete  or  respond  to  the  following: 
1.  Name  tre  two  layers  of  Earth's  crust 
2.   What  is  the  radius  of  Earth?         km. 
3.  Name  three  factors  affecting  the  thickness  of  main 
thermocline. 
4.   The  layer' below  the  sound  channel  axis  is  termed  the 
5.  The  troposphere  extends  to  a  height  of 
kms  near  the  equator. 
6.  The  Ozor.e  layer  has  a    lapse  rate,
7.  One  degree  is  equal  to  _____   __  divided  by 
8.  Record  the  approximate  coordinates  of  each  of  the 
following  locations: 
Nome,  Alaska,  USA 
Peiping,  China 
Sydney,  Australia
Instruction  Section  SW  G3ABR99105  000-V-4 
Lowry  Air  Force  Base,  Colorado  18.0ctobet.L9B4 
WAVE  PROPAGATION 
03JECTIVES 
o   Given  five  statements  describing  phenomena  associated 
with  geognosy,  select  those  statements  relating  to  wave 
propagation. 
o   Given  three  illustrations  associated  with  different  types 
of  particle  motion  and  seven  descriptive  phrases  and 
terms,  associate  the  phrases  and  terms  with  the 
appropriate  illustration ( s ) . 
o   Complete  five  statements  explaining  the  mechanics 
of  wave  propagation. 
o   Given  a  list  of  three  physical  properties  of  gaseous, 
liquid,  and  solid  media,  match  each  property  to  a 
statement(s)  describing  its  affect  on  wave  propagation. 
INTRODUCTION 
From  previous  units  of  instruction  it  is  known  that  three  of 
the  monitoring  systems  utilized  by  AFTAC  are  designed  to  detect 
waves  generated  by  the  detonation  of  a  nuclear  device. <  Each 
syscem,  the  seismic,  hydroacoustic,  and  EM?,  operates  in  a 
separate  medium  giving  rise  to  the  question  of  how  waves 
prccagate  in  each  media.  To  answer  this  question  we  will  review 
the* states  of  matter,  define  the  properties  of  a  wave,  describe 
the  particle  notion  associated  with  principal  wave  types,  and 
discuss  the  mechanics  of  wave  propagation.  Finally,  we  will 
study  the  physical  properties  of  each  media  and  how  these 
properties  affect  wave  propagation. 
INFORMATION 
NATURE  OF  MATTER 
Matter  exists  in  three  states:  solids,  liquids,  and  gasses. 
A  sclid  is  a  substance  that  displays  a  definite  shape  and 
c**ir.ita  volume.   A  licuid  takes  the  shape  of  its  container  and 
has  *  definite  volume.  A  gas  Lakes  the* shape  cf  its  container 
and  has  the  same  v  lume  as  the  container. 
The  molecules  _f  a  solid  are  fixed  in  relationto  each  other. 
They  do  vibrate  back  and  forth  through  their  position  of
equilibrium  but  are  so  close  together  that  they  can  be  compressed 
only  slightly.   Solids  are  normally  crystalline  substances,  that 
is  their  molecules  are  arranged  in  a  definite  pattern.   Because 
of  this  solids  tend  to  hold  their  shape  and  have  a  definite 
volume. 
The  molecules  of  a  liquid  are  not  fixed  in  relation  to  each 
other.  They  normally  move  in  a  flowing  motion  but  are  still  so 
close  together  that  they  are  practically  incompressible,  thus 
have  a  definite  volume.  Because  the  molecules  move  in  a  smooth, 
flowing  notion  and  not  in  any  fixed  manner,  a  liauid  takes  the 
shape  of  its-  container. 
The  molecules  of  a  gas  are  not  fixed  in  relation  to  each 
other  and  move  rapidly  in  all  directions,  colliding  with  each 
other.  They  are  much  farther  apart  than  the  molecules  of  a 
liquid,  and  extremely  far  apart  when  compared  to  the  molecules  of 
a  solid.   The  movement  of  gas  molecules  is  limited  only  by  its 
container,  therefore,  a  gas  takes  the  shape  of  its  container. 
Because  the  molecules  are  far  apart,  a  gas  is  easily  compressed 
and  has  the  same  volume  as  its  container. 
PROPERTIES  OF  WAVES 
A  wave  is  simply  a  disturbance  that  travels  through  a  medium. 
This  disturbance  may  be  a  displacement  of  atoms  from  their 
equilibrium  positions  in  any  elastic  medium,  a  variation  in 
pressure  in  a»gas,  or  more  simply  a  pulse  sent  along  a  rope  that 
is  fixed  at  one  end.  In  any  case,  a  wave  represents  a  transfer 
of  energy  in  the  direction  of  propagation  of  the  disturbance.  A 
wave  m.*.y  be  a  single  pulse  disturbance,  like  the  sound  heard  when 
one  clars  their  hands,  or  a  wave  train.  A  wave  train  results 
when  the  source  is  periodic,  like  the  sound  heard  when  an  entire 
audience  applauds.  .  Regardless  of  the  source  there  are  certain 
characteristics  of  -waves  that,  for  the  sake  of  convention, 
require  definition.   (Refer  to  Figure  10). 
Figure  10 
WAVE  TRAIN  CHARACTERISTICS
Characteristics 
The  amplitude  of  a  wave  (A)  is  the  maximum  displacement 
possible  when  measuring  peak  to  trough.  The  wavelength, 
(lamda),  is  the  length  of  the  period  of  the  disturbance  pattern, 
norually  a  metric  unit  of  length.  The  period  (T)  is  the  time 
required  for  a  wavelength  to  pass  a  po;nt  on  the  x-axis.   The 
reciprocal  of  the  period  (1/T)  is  called  the  frequency  (f)  of  the 
wave,  and  is  the  number  of  complete  oscillations  per  unit  of 
time.  One  oscillation  per  second  is  called  a  hertz  (Hz)  or  cycle 
per  second  (cps) .  The  velocity  (v)  of  propagation  of  a  wave  is 
the  wavelength  divided  by  the  period  and  is  expressed: 
or    X  f 
The  value  obtained  from  this  formula  is  the  speed  that  the 
disturbance  is  moving  along  the  x-axis;  it  also  represents  the 
speed  that  energy  is  being  transmitted  along  the  x-axis.   It  must 
be  emphasized  that  no  medium  is  transferred  by  the  wave,  only 
energy.  Matter  may  move  about  an  equilibrium  point  but  there  is 
no  net  transfer  of  matter.  This  is  visualized  by  observing  a 
bouy  in  the  ocean.  The  bouy  bobs  up  and  down  as  the  waves  pass, 
but  does  not  move  horizontally.  The  energy  has  been  transmitted, 
not  the  matter. 
Waves  are  generally  divided  into  two  categories-,  longitudinal 
and  transverse.  A  longitudinal  wave  is  one  in  which  the 
displacement  (particle  motion)  is  in  line  with  the  direction  of 
propagation  and  therefore,  direction  of  energy  transfer.  A 
transverse  wave  is  one  in  which  the  particle  motion  is 
perpendicular,  or  at  right  angles  to  the  direction  of  wave 
propagation.  More  in  depth  study  of  particle  motion  is  provided 
later,  however,  it' is  important  to  restate  that  there  is  no  net 
transfer  of  material,  only  energy,  associated  with  both  wave 
types. 
Waves  exhibit  a  quality  referred  to  as  superposition.  As  two 
waves  simultaneously  pass  through  a  region  they  merge  to  form  a 
new  wave  in  that  region. 
Waves  that  are  in  phase  when  passing  through  a  given  region 
combine  to  produce  a  wave  with  a  greater  displacement  (A)  while 
the  period  (T)  remains  constant.  This  is  referred  to  as 
CONSTRUCTIVE  INTERFERENCE  and  is  illustrated  in  Figure  11. 
*  Waves  that  are  one  half  wavelength  (130°)  out  of  phase  combine 
to  produce  a  wave  with  no  displacement,  effectively  cancelling 
each  other.  This  is  referred  to  as  DESTRUCTIVE  INTERFERENCE  and 
is  illustrated  in  Figure  12.
AX       AX       /A 
\y     \y 
V 
"X,s  ^M^^r  '^#L- 
Figure  12 
DESTRUCTIVE  INTERFERENCE
Waves  from  a  periodic  source,  such  as  a  seismic  disturbance, 
undergo  these  processes  many  times  and  are  therefore  very  complex 
in  their  appearance. 
PARTICLE  MOTION 
As  stated  earlier,  waves  are  classified  by  the  particle 
motion,  or  observed  molecular  movement,  the  disturbance  causes. 
Longitudinal,  transverse,  and  elliptical  retrograde  are  the  three 
classifications  most  important  to  the  study  of  detection  systems. 
Longitudinal'. 
As  a  disturbance  passes  through  a  medium  the  individual 
molecules  are  set  in  motion  about  their  normal  rest,  or 
equilibrium,  position.  A  longitudinal  wave  causes  this  vibration 
to  be  in  line  with,  or  parallel  to,  the  direction  of  wave 
propagation.   Refer  to  Figure  13. 
B 
Figure 
LONGITUDINAL 
WAVEFRONT 
This  illustration  depicts  the  passing  of  a  longitudinal 
wavefront  (x)  through  a  solid  medium.  Molecules  A  and  B  have 
already  transferred  the  energy  associated  with  the  wavefront  and 
continue  to  cscillate  through  their  respective  rest  positions. 
The  inertia  of  the  energy  transfer  from  molecule  B  to  molecule  C 
has  caused  C  tc  overshoot  its  normal  rest  position  and  strike 
molecule  D.  The  energy  is  subsequently  transferred  to  D  and  the 
wave  continues  to  propagate  in  this  fashion. 
Longitudinal  particle  motion  is  referred  to  by  many  names, 
all  describing  the  observed  molecular  motion.  A  few  of  the 
alternate  names  are:  compressional-rarefactional,  compressional-
dialational,  and  push-pull.   Figure  13  is  a  common  illustration 
of  longitudinal  particle  motion.   Note  that  a  slight  change  in 
volume  occurs. 
Transverse. 
Transverse  waves  result  in  the  displacement  of  molecules 
perpendicular  to  the  direction  of  wave  propagation. ~  That  is  to 
say  that  the  particles  move  at  right  angles  to  the  disturbance. 
This  phenomena  is  easily  illustrated  by  securing  one  end  of  a 
length  of  rope,  stretching  it  taut,  and  quickly  jerking  the  free 
end.  The  resulting  motion  in  the  rope  is  actually  a  transverse 
wave.  Figure  14  illustrates  this  type  of  wave. 
"  ••   i  •   1 
*  t   .  *   .       t 
• 
. 
1       . 
Figure  14 
TRANSVERSE  WAVE 
In  nature  this  wave  results  from  the  release  of  a  shearing, 
or  twisting,  force  that  has  been  applied  to  a  substance. 
However,  unlike  the  longitudinal  wave,  transverse  waves  propagate 
only  in  solids.  The  shear  elasticity  of  fluids,  or  matter  in 
which  the  attractive  forces  between  molecules  permits  flow 
(liquids  and  gasses),  is  insufficient  to  support  this  type  of 
wave. 
Many  terms  are  used  to  describe  the  transverse  wave.   Shear 
is  most  common,  and  describes  the  type  of  force  that  generates 
the  wave.  Ecui voluminous  and  transverse  both  describe  the 
particle  motion  associated  with  the  disturbance.   Figure  15  is  a 
cosuaon  illustration  of  a  transversa  wave.   Note  that  there  is  no 
change  in  volume,  simply  shape.
7 //////// /.SBS 
Bslfellf 
n    [J 
i,  i  i  i  i. 
Figure  15 
TRANSVERSE  WAVE  MOTION 
Elliptical  Retrograde. 
The  particle  motion  associated  with  this  type  of  wave  is 
depicted  in  Figure  16.  Note  both  the  horizontal  and  vertical 
motion  of  the  particles.  This  wave,  commonly  referred  to  as 
Rayleigh,  is  only  observed  on  seismological  records  and  further 
discussion  is  deferred  to  units  of  instruction  dealing  with 
seismology. 
>     }    !     I      •     I 
l<   )'  )<    /  l—r— 
3? 
■i  ■;  r  /  r  f  >'  t  >  i   ;'  /  f  >'  i 
U±i 
i_L-_Q. 
t  t 
ffl 
an 
i  I  i  t  t  t  t  i  t  i  i  i  i  i  i 
'  '  » ' > |  i  rn 
I  i  i  i  i MS 
t  i 
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Figure  16 
ELLIPTICAL  RETROGRADE  MOTION
MECHANICS  OF  WAVE  PROPAGATION 
The  information  presented  thus  far  makes  it  obvious  that  the 
Earth  and  its  constituent  parts  are  not  homogeneous  mediums, 
meaning  they  are  not  comprised  of  the  same  materials  throughout 
and  are  therefore  layered.   This  layering  has  definite  effects  on 
wave  propagation.   A  wave  generated  in  a  homogeneous  substance 
will  not  change  in  appearance  despite  the  distance  travelled, 
however,  layering  has  drastic  effects  on  wave  appearance. 
When  a  wave  is  incident  upon,  or  strikes,  the  interface 
between  two  mediums,  a  portion  of  the  wave  may  enter  the  new 
medium  and  change  direction.  This  portion  of  the  wave  is  said  to 
refract.  That  portion  of  the  wave  that  strikes  the  interface  but 
remains  in  the  medium  is  said  to  reflect. 
Reflection. 
The  law  of  reflection  requires  the  angle  of  reflection  to 
equal  the  angle  of  incidence.  The  angle  of  incidence, $  ;  is  the 
angle  the  wave  makes  with  a  normal,  or  a  line  perpendicular  to 
the  interface  between  two  layers.   The  angle  of  reflection, $  ; 
is  the  angle  the  reflected  wave  makes  with  the  normal  to  the r 
interface.   These  facts  are  illustrated  in  Figure  17. 
Figure  17 
ANGLE  OF  REFLECTION 
If  the  wave  is  travelling  from  a  medium  that  is  denser  to  a 
less  dense  medium,  the  reflected  wave  remains  in  phase  with  the 
incident  wave.   If  the  wave  is  travelling  from  a  less  dense  to  a 
dense:*  medium  the  reflected  wave  is  out  of  phase  with  the 
incic  :nt  wave.  These  phenomena  can  be  demonstrated  with  a  rope. 
If  one  erd  is  left  free  and  a  pulse  (wave)  is  sent  along  the
rope,  the  free  end  responds  with  increased  displacement,  like  a 
bullwhip.  When  the  wave  arrives  at  the  free  end  the  reflected 
wave  is  in  phase  and  contructive  interference  results.   If  the 
end  of  the  rope  is  secured  to  a  heavier  rope,  or  chain,  the 
reflected  wave  is  out  of  phase  with  the  incident  wave  and 
destructive  interference  occurs. 
Refraction. 
That  portion  of  a  wave  that  enters  the  new  medium  and  is 
transmitted .through  it  is  said  to  be  refracted.  Refraction  obeys 
Snell's  Law,  that  states  mathematically,  a  wave  travelling  from  a 
denser  medium  to  a  less  dense  medium  is  refracted  away  from  the 
normal  v/ith  the  interface.  A  wave  travelling  from  a  less  dense 
to  a  denser  medium  is  refracted  toward  the  normal  with  the  inter- 
face. This  is  illustrated  in  Figure  18. 
Figure  18 
ANGLE  OF  REFRACTION 
Diffraction. 
As  the  angle  cc  incidence  of  a  wave  approaches  90°  the  wave 
is  neither  reflected  nor  refracted  but  diffracted.  The  wave,  in 
essence,  does  not  reflect  but  attempts  to  travel  around  what  it 
sees  as  an  obstacle.   If  you  place  a  rock  in  a  stream  of  water, 
the  w-.ter  flows  around  the  obstacle.  Of  course,  this  is  a  simple 
a. .aloe/  of  a  complex  problem,  but  it  does  illustrate  diffraction. 
Figure"  15  depicts  the  phenomena  of  diffraction.
Figure  19 
DIFFRACTED  WAVE 
PHYSICAL  PROPERTIES  OP  MATTER 
Our  earlier  discussions  were  limited  to  types  of  matter/ 
properties  of  a  wave,  and  the  particle  motion  associated  with 
different  wave  types.  But,  the  study  of  detection  systems 
requires  more.  After  all,  we  are  concerned  with  detecting  waves 
generated  by  explosions. 
By  this  time,  you  must  have  realized  that  there  is  a  lot  more 
to  wave  propagation  than  simply  a  disturbance  travelling  through 
a  substance.  You  may  be  asking  questions  like  this  ...  Do  all 
states  of  matter  possess  the  same  physical  properties?  Do  these 
physical  properties  affect  wave  propagation?  Are  these  factors 
interrelated?  This  material  is  designed  to  answer  these 
Questions  and  more. 
i 
Solids. 
As  stated,  solids  have  a  definite  shape  and  definite  volume. 
Additionally,  the  molecules  of  a  solid  are  normally  arranged  in  a 
definite  pattern  (crystalline).  Moreover,  most  solids  display 
certain  properties  (i.e.,  density,  elasticity). 
DENSITY.  Density,  a  property  of  all  matter,  is  defined  as 
the  mass  per  unit  volume  and  is  expressed: 
D  = 
where  D  is  the  density 
m  is  the  mass,  and 
v  is  the  volume
Density  is  normally  expressed  in  Kg/m3,  Generally  speaking,  the 
density  of  a  material  decreases  as  temperature  increases  and 
increases  as  temperature  decreases. 
ELASTICITY.   All  objects  become  deformed  when  an  outside 
force  is  applied  and  changes  its  shape  or  size.   The  objects 
ability  to  return  to  its  original  shape  and  size  after  removing 
the  force  is  called  elasticity.  When  force  is  applied,  the  mole- 
cules of  a  solid  either  repel  or  attract  each  other.  For 
instance,  if  a  rubber  ball  is  pulled  out  of  shape  and  then 
released,  the  ball  returns  to  its  original  shape.   The  attractive 
forces  of  the  molecules  cause  this.  Conversely,  if  the  ball  is 
squeezed  and  released  the  ball  again  returns  to  its  original 
shape.  By  squeezing  the  ball  its  molecules  have  been  forced  too 
closely  together  and  they  repel  each  other.  In  summary,  if  the 
molecules  of  a  solid  are  slightly  pulled  apart  they  attract  each 
other  and  if  compressed  they  repel  each  other. 
If  too  great  a  force  is  applied,  a  solid  can  not  return  to 
its  original  size  and  shape.  When  this  occurs  the  elastic  limit 
of  the  object  has  been  exceeded.  For  instance,  if  a  spring  is 
stretched  beyond  its  elastic  limit  it  can  not  return  to  its  ori- 
ginal shape.  The  molecules  of  the  spring  have  been  pulled  far 
enough  apart  that  their  normal  attractive  forces  cannot  return 
the  spring.  If  too  much  tension  is  applied  the  spring  breaks. 
These* facts  are  illustrated  in  Figure  20. 
Spring  fcx(or«  iuetching.  Sprir«  ttretchcd  nut  its  elastic  limit. 
Sprin?  stretched  t«yond  it*  elastic  limit.  Sprino.  stretched  much  t-eyond  iu 
clastic  limit ...  britk  occursi 
I 
Figure  20 
ELASTICITY 
Elasticity  is  measured  in  a  number  of  ways.  Whenever  an 
object  is  defcrmed  by  an  outside  force  the  molecular  forces  of 
the  object  tend  to  resist  the  change  in  shape  and/or  volume. 
Stress  is  a  measure  of  the  tendency  of  an  object  to  return  to  xts
original  shape  and  size  after  a  deforming  force  is  removed. 
There  are  five  basic  stresses:   tension,  compression,  shear, 
twisting  and  bending.   Each  form  of  stress  is  illustrated  in 
Figure  21.   More  specifically,  stress  is  defined  as  the  ratio  of 
the  outside  applied  force  that  causes  the  distortion  to  the  area 
over  v/hich  the  force  acts.   This  is  expressed  by  the  following 
formula: 
stress  * 
aDDlied  force 
area  over  which  the  force  acts 
or 
■■! 
where  S  if  the  stress 
F  is  the  force,  and 
'A  is  the  area  over  which  the  force  acts. 
The  metric  stress  unit  is  usually  the  pascal  (Pa)  and  is 
expressed: 
lPa  *  lN/m2  (IN  *  .225  lb) 
where: 
N  is  the  weight  of  an  object  in  New tons, 
and  m2  is  the  area  acted  upon  in  square  meters. 
i 
T 
Tcntien 
CD 
Comprcsiofl 
n 
Shear 
Twining 
I  --^         1 
— -^ i  -v 
Sending 
Figure  21 
FORMS  OF  STRESS
Whenever  stress  is  applied  to  an  object  the  object  is 
deformed.   The  resulting  deformation  is  called  strain.  That  isr 
strain  is  the  relative  amount  of  deformation  of  a  body  that  is 
under  stress.   Strain  is  a  measure  of  the  change  in  length  per 
unit  of  length,  change  in  volume  per  unit  of  volume,  and  so  on. 
Simply  stated,  strain  is  a  direct  consequence  of  stress. 
PRESSURE.  When  force  acts  perpendicular  to  a  surface,  the 
pressure  exerted  on  the  surface  is  given  by  the  formula: 
F 
where  P  is  the  pressure 
F  is  the  force,  and 
A  is  the  area  of  the  surface. 
Pressure,  like  stress,  is  measured  in  pascals. 
Examination  of  the  given  formula  shows  that  a  decrease  in 
area,  with  equal  force  applied,  results  in  dramatic  increases  in 
pressure. 
ELASTIC  MODULUS.   A  basic  law  relating  to  the  elasticity  of 
solids  is  Hooke's  Law  that  states  "stress  is  directly  propor- 
tional to  strain  as  long  as  the  elastic  limit  has  not  been 
exceeded".   In  other  words,  strain  continues  to  increase  propor- 
tionally with  stress.  Beyond  -this  point  (elastic  limit) ,  the 
material  is  permanently  deformed;  with  further  stress  applied  the 
material  finally  breaks.   This  proportionality  constant  between 
stress  and  strain  is  termed  the  elastic  modulus  and  is  stated: 
stress  *  (elastic  modulus)  x  (strain) 
or 
elastic  modulus  =  f 
. 5f ff 
strain 
This  formula  is  applicable  to  all  types  of  stress. 
E'JLK  MODULUS.   The  volume  of  any  substance  is  decreased  when 
subjected  to  pressure.  As  an  object  is  lowered  into  the  ocean, 
pressure  is  exerted  equally  on  all  sides.   The  pressure  increases 
proportionally  with  depth  and  so  does  the  object's  reduction  in 
volu-e.  This  char.ge  in  volume  is  expressed  as  a  variation  in 
Hooke's  law  and  is  stated: 
stress  =  (elastic  modulus)  x  (strain)
where  the  elastic  modulus  is  called  the  "bulk  modulus" 
and  is  represented  by  0  (beta).  The  stress  is  the  change 
in  force  per  unit  area  (pressure)  and  strain  is  the 
change  in  volume  per  unit  of  volume  (AV/V).   Knowing 
this,  the  bulk  modulus  of  volume  elasticity  may  be 
expressed: 
stress 
strain 
AF/A      AP 
-A  V/V  "  -AV/V 
Again,  as  long  as  the  elastic  limit  of  the  material  is  not 
exceeded  it  returns  to  its  original  shape  and  size  when  the 
external  force  is  removed. 
COMPRESSIBILITY.  The  compressibility,  c,  of  a  material  is 
the  reciprocal  of  its  bulk  modulus  or: 
SHEA?.  MODULUS.   When  the  shape  of  an  object  is  changed  by 
applying -equal  force  in  parallel  and  opposite  directions,  the 
object  is  being  "sheared".  This  is  easily  illustrated  by  placing 
a  book  on  a  table  top  then  pushing  the  top  and  bottom  covers  in 
opposite  directions.  Refer  to  Figure  22.  As  the  shearing  force 
is* applied  the  pages  slide  past  one  another  and  the  book  takes 
the  shape  of  a  parallelogram.  Note  that  no  change  occurs  in  the 
volume. 
Figure  22 
SHEARING  ACTION
The  shearing  stress  is  csfined  as  the  change  in  force  per 
unit  area  {  a  F/A)  and  the  shearing  strain  as  the  amount  of 
lateral  displacement  per  unit  height  (x/h) .  This  is  yet  another 
variation  of  Hooke's  Law  and  is  stated: 
stress  a  (elastic  modulus)  x  (strain) 
where  the  elastic  modulus  is  called  the  shear  modulus. 
Therefore,  the  shear  modulus  (S)  may  be  expressed 
S  =  stress  _   A  F/A 
strain  ~  x/h 
The  effect  of  these  forces  on  the  propagation  of  a  wave  is 
easily  understood  by  examining  the  formula  foe  the  velocity  of 
seismic  waves. 
The  velocity  of  the  compress ional  wave  (Vp)  is  determined  by 
the  formula 
VP  s     /(  6  +4/3  S)/p 
where       s  is  bulk  modulus, 
S  is  shear  modulus,  and 
p.  is  the  density  of  the  medium. 
Gases. 
.  EXPANSION.  Expansion  is  the  property  of  a  gas  that  causes  it 
to  completely  occupy  the  volume  of  its  container. 
DIFFUSION.  Diffusion  is  the  property  of  a  gas  that  allows  it 
to  combine  with  the  molucules  of  a  solid  or  liquid. 
A  balloon  inflates  because  of  the  pressure  of  gas  molecules 
on  the  inside  surface  of  the  balloon.  This  pressure  results  from 
the  collision  of  the  rapidly  moving  molecules  with  the  walls  of 
the  balloon.   The  pressure  may  be  increased  by  blowing  into  the 
balloon  or  heating  the  molecules  present.   Seat  increases  the 
velocity  of  the  molecules. 
Liquids 
A  liquid  is  a  substance  that  has  definite  volume  and  assumes 
the  shape  of  its  container.   The  molecules  move  in  a  flowing 
motion  but  are  so  close  together  that  they  are  difficult  to 
compress. 
VISCOSITY.  One  characteristic  of  liquids  is  called  flow.  In 
liquids  there  is  friction,  called  viscosity.  The  greater  the 
molecular  attraction,  the  greater  the  friction  and  the  greater 
the  viscosity.
If  a  liquids  temperature  is  increased,  its  viscosity 
decreases.   An  increase  in  temperature  causes  an  increase  in  the 
distance  between  molecules,  reducing  the  molecular  attraction. 
COHESION.  The  attractive  forces  between  like  molecules 
causes  a  liquid  to  be  sticky. 
ADHESION.  The  attractive  force  between  unlike  molecules  is 
called  adhesion. 
A  liquid  whose  adhesive  forces  are  greater  than  its  cohesive 
forces  tends  to  leave  wet  any  surface  it  comes  in  contact  with. 
A  liquid  whose  cohesive  forces  are  greater  than  its  adhesive 
forces  leaves  dry  any  surface  it  comes  in  contact  with.
EXERCISE  3 
Procedure: 
Complete  or  respond  to  the  following: 
1.  The  molecules  of  a  liquid    fixed  in 
relation  to  each  other. 
2.  A  wave  train  results  when  the  source  is 
3.   A  longitudinal  wave  causes  particle  motion 
to  the  direction  of  propagation. 
4.  What, are  two  alternate  names  for  transverse  particle 
motion? 
5.  The  law  of  reflection  requires  Oi  to  equal  the 
6.  Diffraction  occurs  when  0^  approaches
7.  How  is  density  defined? 
8.  How  is  strain  defined? 
9.  The  metric  unit  of  stress  is  usually  the 
10.  When  the  elastic  limit  of  a  material  is  exceeded  the 
.  material 
  . 
 ' 
 ______