Miniature X-Ray
Mini-X2
Mini–X2 is a miniature
X-ray tube system, which includes the X-ray tube, high voltage powerSource®

supply and USB controller. It is designed for X-ray fluorescence analysis applications (XRF).
Features

Applications• USB controlled• X-Ray
Fluorescence(XRF) analysis• Stable output• Fast• Low power• Portable systems• Small• OEMOptions
Power: 4 W or 10 W

• Research• Process Control• Teaching

HV: 50 kV or 70 kV
Target: Ag, Au, Rh, or W
The Mini-X2 is a miniature X-ray tube system which includes the X-ray tube, the power supply, the control
electronics, and the USB communications to the computer. It is optimized for compact X-ray fluorescence (XRF)
applications.
The Mini-X2 consists of two components: the Mini-X2 X-ray tube module and the Mini-X2 Controller. The X-ray
tube module includes the tube and HVPS. Several different options are available: 1) maximum power can be 4Wor 10W; 2) maxium HV can be 50 kV or 70 kV; and 3) the anode can be Ag, Au, Rh, or W and several custom
variations can be provided (www.amptek.com). The Controller includes the USB communications and software
control. It can be configured, via software, to support any of the X-ray tube modules. A 10 pin flex cable connects
the Controller and the X-ray tube module. Connections to the Controller are 12VDC power, USB for command andcontrol, and an AUX connector with a safety inter- lock and a driver for a warning light.
The Mini-X2 is a replacement for Amptek’s previous Mini-X product family. The X-ray Tube Module is similar tothe previous Mini-X-OEM. The Controller has significantly improved control features, including software
configurability and faster control and readback. It utilizes a completely different software interface, based upon
the FW6 protocol used with Amptek’s digital pulse processors.

Mini−X Output X-Ray Spectra
Ag Target @ 50 kV

Au Target @ 50 kV

Ag Κα

Au Lα
CountCountLog

Au
Lβ

Au

Ag ΚβLγThe Mini−X2 is based on the Newton Scientific Inc. miniature X-ray sources.

AMPTEK INC.

Amptek.sales@ametek.com

Log

www.amptek.com

Linear

Specifications
Mini-X2 X-Ray Tube Module

Mini-X2 X-Ray Tube Module

X-Ray Tube PerformanceConnectors

Target Material

Silver (Ag), Gold (Au), Rhodium(Rh), Tungsten (W)Target Type
Tube Voltage
Tube Power
Tube Current

Transmission
10 to 50 kV or 35 to 70 kV
4 W or 10 W available
5 µA to 200 µA (Fold back forpower limit)

PowerUSB
Interlock3 pos receptacle, 0.031” (Hirose)Standard Mini-USB
4 pos terminal block, female
sockets, 0.15” pitch

Mini-X2

10 pos latching ribbon, male, 0.10”pitch

Typical Dose Rate
Au & W
Ag & Rh

PowerTested @ 30 cm on axis
1 Sv/hr (100 rem/hr) at 50 kV and80 µA (4 W)
2.2 Sv/hr (220 rem/hr) at 50 V and80 µA (4 W)

Typical Flux
Approximate flux values are tested @ 30cm on axis. Units are
the following: counts/second/mm2/uA
6 x 104
Ag & Rh

Au & W
Leakage Radiation

2 x 10

Input Voltage

11.5 to 12.5 V

Input Current
PowerConsumption

1.5 A max
4 W Tubes: 9 W @ full power 10 W
Tubes: 18 W @ full power

SafetyControls2) USB enable command Tube
shuts off if USB is lost5< 5µSv/hr (0.5 mrem/hr) at 5 cmwith safety plug installedIndicators

Ag & Rh
Au & W

0.75 ±0.1 µm
1 ±0.1 µm

PhysicalWindow
Focal Spot
Settling Time
Cathode TypeHV Polarity

125 µm Be (window grounded)
Approx. 2 mm
0.5 s (typical)
Tungsten filament
Grounded anode

HV Stability< 0.1%

Operating Temp
Storage Temp
Humidity
Cooling-10 to +50 °C-25 to +60 °C
30 to 90% non-condensing
Air cooled

Weight< 400 g1) Flashing LED
2) Beeper3) External lamp driver

Target Thickness

Environmental & Physical1) Safety interlock (with fail-safe
lamp driver)Dimensions
Weight2.270 x 2.770 x .770 in85 g

Radiation Precautions
The Mini−X2 generates x-ray radiation during
normal operation. The Mini−X2 has been designed tofocus radiation in the designated output direction,
however radiation in other directions is possible andshould be addressed with shielding and/or monitoringin the final application.
Radiation Levels external to the X-ray tube housing withthe brass safety plug ON do not exceed 25 µS/h (2.5mrem/h) measured 5 cm from the surface of thehousing in accordance with Requirements 5.2.2.2.2 of
the American National Standard N43.2.

Examples of shielding the 4 W, 50 kV Ag anode tube (that comply with the above standard)
1 mm (0.040 inch) of Pb will result in radiation levels of 0.5 mrem/h.
6.35 mm (0.250 inch) of Fe will result in radiation levels of 0.5 mrem/h.
3.18 mm (0.125 inch) of Brass will result in radiation levels of 2.5 mrem/h.
The inside of the housing can also be lined with 3.18 mm (0.125 inch) of aluminum (Al) in order to absorb the XRF from theshielding material.

CautionThis device produces X-Rays when energized. To be operated only by qualified personnel.

Mini−X2 Mechanicals
Mini-X2 Mechanical Dimensions

Mini-X2 50 kV Isopoer Curve (Max. 4Watts)

Mini-X2 120°Cone
120° X-Ray Cone

Mini-X2 Angular Response
100

Normalized Counts(%)

8060

Be40200-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

How does the Mini-X2 differ from Amptek’s existing Mini-X products?
The Mini-X2 provides many additional control parameters and much better
hard- ware monitoring than the first generation Mini-X. It provides a much fasterreadback and assessment that the tube is operating nominally. It allows one toeasily reconfig- ure, via software rather than hardware, different tube parameters.
The safety interlock includes a failsafe lamp driver and software configurability. It
provides more complete fault monitoring and the ability to over-ride defaults.
The Mini-X2 controller has the same physical form factor as the MX-50,
operates on the same voltages, draws the same current, and still communicates
via USB. The INTERLOCK connector has a different pinout. The software interface
is completely dif- ferent: new USB drivers, new command set, new parameter set,etc. A new version of the application software is required; all of the existing
operations will still exist, with little change, but a menu of advanced settings will
be added. For customers writing their own software, their code will need to be
replaced using a new set of subroutines.

APPLICATION NOTES

Safety Interlock

The AUX connector on the Mini-X2 Controller contains a safety
interlock, designed for use with a failsafe warning lamp. A typicalapplication circuit is sketched below. The controller applies a
configurable voltage across the external interlock circuit andmonitors the current; the tube is only enabled if the current iswithin a programmable range. It turns off if the switch is open or if
the lamp fails.

Warning lamp and beeper
The Mini-X2 controller includes an LED and a beeper which indicate that the tube’s HV and current are enabled.
They flash/beep at about 1 Hz. The safety interlock drives a lamp with a failsafe circuit. See the Mini-X2 User
Manual for warning lamp technical specifications.

Filters and Collimators
In XRF, the characteristic X-rays of a given element (theanalyte) are only stimulated by incident X-rays with energy above
the analyte’s absorption edge (and most efficiently by thosebetween 1.5 and 2 times the absorption edge). An X-ray tube
produces X-rays across a broad continuum (brehmstrahlungspectrum) extending below the absorption edge; thesecontribute to spectral background and degrade the precision,accuracy, and detection limits of an analyte. Filters (and HVsettings) are used to reduce the background for a particularanalyte and are key to high quality XRF measurements. See theMini-X2 User Manual for more information.

Software
The Mini-X2 is provided with software which allows the user to set
the HV and current, enable or disable the tube, to set various
configuration parameters, and to read back the unit’s status. Amptekalso provide a software developer’s kit (SDK) for customers whoneed to write their own control software. The Mini-X2 softwareinterface is based on Amptek’s FW6 communication protocol, via
USB. It is completely different from the software interface on theoriginal Mini-X.

®

AMPTEK INC. 14 DeAngelo Drive, Bedford, MA 01730-2204 USA+1 781 275-2242 Fax: +1 781 275-3470 Amptek.sales@ametek.com

www.amptek.com

Choosing the anode material
Amptek’s Mini-X is available with silver (Ag), gold (Au), rhodium (Rh) or tungsten (W) as the anodematerial. A common question is: Why would I pick one material versus another one? In general, theexcitation spectrum depends on the tube material. The plots below shows the spectra from the tubes,
at 50 kV and 80 A.
Spectra from different Mini-X models
AgW L peaks

AuCounts

RhW
Au L peaks

Rh K peaks

Ag K peaks
Brehmsstrahlung continuum

0102030405060

Energy (keV)

How does this impact XRF analysis?
oTo best measure the characteristic X-rays of any single element, the analyte, one should excite
with X-rays with an energy about 1.5 to 2 times the element’s K edge, and with the backgroundcontinuum low at energies near the characteristic lines.

oThe spectrum of X-rays emitted by a tube has two components: a continuum (frombremsstrahlung) and lines (from the characteristic X-rays of the anode materials).

oAt high energies, the spectrum arises entirely from the continuum; to measure analytes at thesehigh energies, one wants a source with an intense continuum. The intensity of bremsstrahlung
increases with atomic number, so the intensity of the continuum and total intensity are higher
for the Au and W anodes than Ag and Rh.

oThe characteristic X-ray lines are clearly seen in the spectrum above; Ag and Rh have higher
energy characteristic X-rays.
 Using excitation from these lines can improve signal to background relative to using thecontinuum as the primary excitation. These energies will be well suited to excite someelements but not for others. The Ag K lines, for example, are well suited to excite arange of metals from Cr through Mo.
 These energies may interfere with elements in the sample. The Au and W L lines
interfere with several metals of common interest. The Ag lines make it difficult tomeasure Ag in a sample.
 The strong K line from Ag and Rh produces clear backscatter peaks from Rayleigh andCompton scattering. Some algorithms use this ratio to estimate sample atomic number;this is much harder with the Au and W, due to the many L lines.
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The plots below show spectra taken from a calibration standard (multiple elements in a glassmatrix) using the four different anode materials, with a light filter (10 mil Al) and 50 kVp. The bottom
plot is normalized. Each tube produces different ratios for the intensity of the analytes and produces
different scattered characteristic X-rays from the anode.
XRF spectra from different Mini-X models
Zn K

AgAs K

AuRh

Zr K

Cd K
Ti K

Zr bCounts

Cd Kb

Ba K

Ba K

Rh backscatter peaks

0W51015Ag backscatter peaks

2025303540

Energy (keV)

Normalized Counts

XRF spectra from different Mini-X models

Ag05Rh1015

Energy (keV)

2AuW

2025

General advice for anode selectionoSilver (Ag) is probably the most commonly used material. This is in part legacy (much software
was built around 109Cd as an excitation source). The clear 22.1 keV peak provides goodexcitation for many elements of most common interest and provides a clear backscatter ratio,
for those using the scattered intensity method to characterize the matrix.

oRhodium (Rh) is very similar to Ag but it permits one to measure Ag in samples. Rh is relatively
rare so is less likely to be an interference concern.

oGold (Au) produces about twice the continuum intensity. One can use filters to shape thespectrum and retain and higher total count rate. It is particularly useful for analytes with a Kedge above the silver lines, where the continuum alone produces the excitation. Moreover, theL lines of gold are low enough energy to easily filtered out, producing an almost pure-continuum
spectrum.

oTungsten (W) is similar to Au but it permits one to measure Au in samples. W is relatively rate
so is less likely to be an interference concern.

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