X-RAY GENERATOR

COOL-X

WITH PYROELECTRIC CRYSTAL

Miniature X-Ray Generator with Pyroelectric Crystal
Battery Operated

APPLICATIONS• Portable X-Ray Instrumentation• Teaching Laboratories• Instrument Calibration• Radiography (X-Ray Film Imaging)• Researcht

esWorld’s Small

2003 WINNERFEATURES

The COOL-X is a novel, miniature X-ray generator
which uses a pyroelectric crystal to generate energetic electrons that produce X-rays in the target
material (Cu). The hermetically sealed package
has a thin beryllium window which allows the Xrays to be transmitted. The COOL-X does not use
radioisotopes or high power X-ray tubes. It is a selfcontained, solid state system which generates X-rays
when the crystal is thermally cycled.
The COOL-X is unique, and should not becompared with other X-ray tubes. It is thermallycycled between 2 to 5 minutes, and does not produce
a constant flux of X-rays. The X-ray flux varies
throughout the cycle and may vary from cycle tocycle, see Figure 4.
The use of the COOL-X in practical applications will challenge the user ’s
imagination!

Be Window
X-RAYS
Low PressureGasTemperature
SensorX -Ray Production
Copper Target
e-e-Pyroelectric
Crystale-

Heater / Cooler

TO-8 Package
Temperature+VGround

COOL-X Output Spectrum from Cu Target

Log
Counts• Miniature size - 0.6” dia x 0.4”        15 mm dia x 10 mm• Low Power: <300 mW• Runs on a standard 9 V battery• Variable end point energy: up to 35 kV• Peak X-Ray flux: 108 photons per second(equivalent to a 2 mCi source)• Solid state: Pyroelectric Crystal• No radioactive sources

LinearEnd PointEnergy0             5           10          15          20           25          30          35Energy (keV)

AMPTEK INC. 14 DEANGELO DRIVE, BEDFORD, MA 01730-2204 U.S.A.
Tel: +1 (781) 275-2242 Fax: +1 (781) 275-3470 email: sales@amptek.com www.amptek.com

Theory of Operation
When heated, a pyroelectric crystal exhibits spontaneous decrease of polarization. Hence, as the temperature
increases, an electric field develops across the crystal. For a specific crystal orientation (-Z face pointing tothe target), the top surface of the crystal gets positively charged and attracts electrons from the low pressure
gas in the environment. As the electrons impinge on the surface of the crystal they produce characteristic
x-rays (Ta) as well as bremsstrahlung x-rays (see Figure 1).
When the cooling phase starts, the spontaneous polarization increases, and the electrons from the
top surface of the crystal are accelerated towards the Cu target which is at ground potential. At this part ofthe cycle Cu characteristic x-rays are produced, as well as bremsstrahlung x-rays (see Figure 2). When thecrystal temperature reaches its low point, the heating phase starts again. The cycle time of the COOL-X
can be varied from 2 to 5 minutes.
Figure 3 shows the typical x-ray spectrum of the COOL-X obtained from the sum of 300 cycles withthe dominant 8 keV peak and the bremsstrahlung continuum. Figure 4 shows a typical COOL-X output
count-rate as a function of time for several heating and cooling phases. The X-ray flux varies throughout
the cycle and may vary from cycle to cycle (see Figure 4).
Ref: J.D. Brownridge and S. Raboy “Investigations of pyroelectric generation of X-rays” Journal of Applied Physics, Vol. 86,
No. 1, 1 July 1999

Figure 1: Heating Phase Spectrum

Figure 2: Cooling Phase Spectrum
CuKα (8.05 keV)CountsCounts

TaLα (8.14 keV)

TaLβ (9.02 keV)

CuKβ (8.90 keV)

TaLγ (10.90 keV)
Energy (keV)

Energy (keV)

Figure 3: Combined Output Spectrum(Heat & Cool, 300 cycles)

Figure 4: Heat and Cool Output Flux
HeatPhase

CoolPhaseCountsCounts3 minutes

Energy (keV)

Cycle

Figure 4 is a typical COOL-X output flux vs Time.  Specificunits may have more counts during the heating or coolingphase, or all of the counts in one of the two phases.

XRF Applications
Multi-Element Fluorescence
PbZn

100%
60%
40%

CountsNormalized Counts (%)

Typical Forward Output
Flux vs. Angle

20%

Ti0%

Zr    -90o    -70o          -35o            0o            35o           70o     90o

Energy (keV)

Angle (Degrees)

Lead (Pb) Fluorescence
PbLαMechanical Dimensions
3.00
2.750

1.50

Counts0.37

PbMαCOOL-X
CuKα
FeKα

2.000

PbLβ

PbLγ
Energy (keV)

0.10

1.12
Red/Green LED

2.25

1.75
0.40
KeyTabMnKαTolerances
x.xx +/- 0.01
x.xxx +/- 0.005
DC Power Jack0.350Be Window

0.71

Aluminum Alloy FluorescenceAll dimensions are in inches

0.12

MnKβ
Cu COOL-X
Counts0.75
0.125
4PLAlNi

Power SwitchEnergy (keV)

COOL-X shown with the Amptek XR-100CR
X-Ray Detector in an XRF application

COOL-X Controller System

The Controller is enclosed inside the metal box. The function of the Controller is to supply power to the X-ray generator,
monitor its temperature, and automatically change the heating and cooling phases of the cycle.  Both a 9 V AC adapter
and a 9 V battery are included.  The battery will provide approximately 6 hours of operation.

COOL-X CONTROLLER SYSTEM
ON/OFFPow er
Sw itchTemperature Monitor
High and Low Temperature
Trigger Points

100/250V AC

9V DC

Flashing LEDOptional 9V
Battery

ACAdapter

Poweron/off

DC Input Jack

ON/OFF
Switchable Voltage Source

58Cool-X

11Indicator Circuit

Red: Heating Phase
Green: Cooling Phase

ACadapterjack

X-RaysHeater Driv e

LED Color and Flash Control
Tone Generator

Bi-Color LED

Beeps at transition ofheating and cooling phases

COOL-X Operation from a 2.5 to 4.5 Volts DC SupplymVTemperature
SensorVoltage
5Heater Voltage

Current Source
1 mA dc+

Off = 0 Volts
On = 2.5 to 4.5 Volts

8COOL-X
Element

X-RAYS

11+-Ground

Lifetime of the COOL-X
When not in use, power to the COOL-X should be turned OFF.  The COOL-X is not designed for continuous operation,
therefore its lifetime will depend on how it is used.
If used intermittently, for about 1-3 hours per day, the estimated lifetime of the COOL-X can be extended to well over1000 hours.  Continuous use of the COOL-X will shorten its lifetime to approximately 200 hours.

Radiation Precautions
The COOL-X is intended to generate x-ray radiation during normal operation. Radiation from all directions is possible and should be addressed with shielding and/or monitoring in the final application. To be operated only by
qualified personnel.
The maximum radiation at the peak of the heating or cooling cycle, at a distance of 10 cm is approximately 5 mSv/hr(500 mR/hr). The peak counting rate at a distance of 10 cm is approximately 200,000 counts/cm2/s. Approximately
75% of these x-rays are low energy below 10 keV.

CautionThe COOL-X is only one component of an X-ray instrument. It is the responsibility of the user, the OEM customer, orexperimenter to provide a fail safe metal enclosure to prevent escaping radiation while using this product. The finalproduct (turn-key system) must comply with local government regulations to protect personnel from exposure toradiation. Amptek Inc., bears no responsibility for the incorrect use of this product.

AMPTEK INC. 14 DEANGELO DRIVE, BEDFORD, MA 01730-2204 U.S.A.
Tel: +1 (781) 275-2242 Fax: +1 (781) 275-3470 email: sales@amptek.com www.amptek.com