Xray

INSIDE lOOK
Above, anx-ray
of a thumbdrive
takenwith Adam
Munich's machine
EDITED BY DougCantor . [email protected]
YOU BUILT WHAT?!
Lateonenight two years ago, Adam
Munich found himself talking with two new
acquaintances ina chatroorn One, a Pakistani
guy, was compLainlng about rolling electricity
blackouts inhis country.The other had broken
his legina motocross accident inMexico and
saidhis local hospital couldn't find a working
x-raymachine.The two situations fused
inMunich'smind; hewondered ifa cheap,
reliable, battery-powered x-raymachine
existed-somethingthat could beused in
remote areas andfunction without being
plugged induring blackouts. After discovering
thattheanswer was no, hespenttwo years
building onehimself outofNixie tubes, old art
suitcases, chainsaw oil, andelectronics from
across theglobe. Itwas anincrediblyambitious
project for anyone, letalone a 15-year-old.
Munich started byreading online about
thescience ofCoolidge tubes, theessential
radiation-emitting core ofmost commercial
machines, andeventually found onefor
sale from a manufacturer inChina. "The
restwas puzzle-solving;' Munich says. "For
something like this, there's no guide:'
He splitthemachine intotwo connected
pieces: a control boxthat houses the
electronics anda second case containing the
x-raytubeandthehigh-voltage components
that drive it. Batteries alone wouldn't provide
enoughpower. He neededavoltage multiplier,
soheborrowed a design originally used
s rURY BY GregoryMone
PHtJTOGR,\ PHS BY LukeCopping
Inhis free timeduring
school, Adam Munich
a x-ray
Tips, Tricks, Hacks and   Projects
Boxfulof '
Radiation
MAY 2012 • POPULAR SCIENCE 71
H2.0
inparticle accelerators. When alternating
current isapplied, itft.ows into a charge-
storing capacitor at itspeak andthenrushes
through a charge-relaying diode when the
polarity ofthecurrent reverses.This second
burst ofcharge combines with the power
stored inthecapacitor, doubling thevoltage.
Using money heearned asa freelance Web
designer, Munich bought enough capacitors
andultrafast diodes oneBay tolink together
four such setups. The voltage increases with
each oneuntil it reaches the75,000 volts
required tospark a decent beam ofx-rays.
Munich, now 18, hasused the machine
tox-ray some household items, including a
penanda computer hard drive.Theoretically,
hesays, itcould beused forhands orlimbs.
Now heisfocused ongetting thecost
under $200 andmaking thedevice sturdy
enough tohelp his friends from thelate-
night chat. Butthecurrent version issure
tohelp with a more immediate concern-
impressing college admissions offices.
72 POPULAR SCIENCE . MAY 2012
,
THESETUP The
machine projects an
x-rayimage onto
a sheet behind the
objectit'saimedat.
HOW IT WORKS
IMAGING
Inside thex-ray tube, a high-voltage
current sends electrons toa tungsten
target.The electrons slam into atoms
inside thetarget, lose energy, andemit
x-rays.The x-rays thenflash ahead and
createa shadow image ofthesubject.
Most machinesusefiat-panel radiation
detectors toget these pictures, butthey
cost about$65,000. InsteadMunich
bought a scintillation screen, a plastic
sheet that turnsfluorescent green
whenit's hitwithionizing radiation.
SAFETY
Munich built hisownGeiger counter
tomeasurethe radiation. The volume
of x-rays coming outof the tubewas
inlinewith hisestimates, andhefound
that the backscatter, oramountof
radiationelsewhere, was verylow. Still
he only uses it outside, aimingit at the
woods behind hishouse. Otherwise
someofthex-rays could bounce offan
interior wallHealso added a speaker
that emitsa warningbuzzwhen the
machine isgenerating x-rays.
INSULATION
Munich placed thehigh-voltage com-
ponents andthe x-raytubeina plastic
junction boxfilled withchainsaw oil.
Hetested the oil's insulating capacity
bydunking twometal plates initand
thensending increasing amounts of
current into one. It took100,000 volts
forthecharge tomove through theoil
from oneplate tothe other. Since the
machineuses only 75,000 volts,the
oilprevents thevoltage from burning
throughthejunction boxorother parts.
DESIGN
Matching artsuitcases, linkedbycable,
enclose thetwopieces ofthemachine.
Munich cut holes inthe lidfor anon/off
switch, meters that monitor current and
voltage, dials toset the exposure time,
anda Nixie-tube display from a Ukrai-
nian supplier that counts theexposure
time down tothetenth ofa second.
MAY 2012 • POPULAR SCIENCE 73
Ready; set, done