Amptek Mini-X-OEM User manual

Mini-X-OEM User Manual Rev D2
AMPTEK, Inc. 14 DeAngelo Drive, Bedford, MA 01730-2204 USA
[phone] Fax: [phone] www.amptek.com [email protected]
Mini-X-OEM X-Ray Tube
MX-50 Controller
Amptek, Inc.
14 DeAngelo Drive
Bedford, MA 01730
PH: [phone]
Fax: [phone]
www.amptek.com
Send sales and technical questions to [email protected]
The Mini-X is based on the Newton Scientific Inc. miniature X-ray source.

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1 Precautions ...........................................................................................................................................3
1.1 High Voltage.................................................................................................................................. 3
1.2 Radiation....................................................................................................................................... 3
1.3 Beryllium Window......................................................................................................................... 3
1.4 Heat and Temperature..................................................................................................................4
1.5 Prop65 Warning ............................................................................................................................ 4
2 Introduction ..........................................................................................................................................4
2.1 Description of Mini-X-OEM and MX-50 Controller .......................................................................4
2.2 Options and Variations .................................................................................................................5
3 Specifications ........................................................................................................................................5
3.1 Mini-X-OEM Specification table.................................................................................................... 5
3.2 MX-50 Specification table .............................................................................................................7
3.3 Output X-Ray Spectra.................................................................................................................... 7
4 Mechanical Interface ............................................................................................................................8
4.1 Dimensions.................................................................................................................................... 8
4.2 Mini-X-OEM Connector................................................................................................................. 8
4.3 MX-50 Connectors .......................................................................................................................9
4.4 Mounting.....................................................................................................................................10
4.5 Cooling ........................................................................................................................................10
5 Electrical Interface ..............................................................................................................................11
5.1 Power Interface...........................................................................................................................11
5.2 MX-50 Voltages...........................................................................................................................11
5.3 MX-50 Interlock...........................................................................................................................11
6 MX-50 Software Interface...................................................................................................................12
6.1 Software Installation...................................................................................................................12
6.2 Operating the Mini-X-OEM with MX-50 ..................................................................................... 14
7 Mini-X-OEM Design.............................................................................................................................16
7.1 X-ray tube....................................................................................................................................16
7.2 High Voltage Power Supply......................................................................................................... 16
7.3 MX-50 Control and Interface Module......................................................................................... 16
8 Mini-X-OEM Accessories.....................................................................................................................16
8.1 Collimator....................................................................................................................................16
8.2 Brass Safety Plug ......................................................................................................................... 17
8.3 Filters...........................................................................................................................................17
9 Radiation Levels and Example Shielding.............................................................................................18
10 Understanding the Interlock and Alarm .............................................................................................18
11 Warranty .............................................................................................................................................21
12 Technical Questions ............................................................................................................................21

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1Precautions
CAUTION: The Mini-X-OEM is only one component of an X-ray instrument. It is the responsibility of the
user, the OEM customer, or experimenter to provide a fail-safe metal enclosure to prevent escaping
radiation while using this product. The final product (turn-key system) must comply with local government
regulations to protect personnel from exposure to radiation. Amptek Inc. bears no responsibility for the
incorrect use of this product.
1.1 High Voltage
The Mini-X-OEM is designed to generate voltages up to 50 kV. The high voltage system is fully
shielded inside the Mini-X-OEM enclosure.
DO NOT ATTEMPT TO ACCESS OR MODIFY THE HIGH VOLTAGE SYSTEM.
DO NOT UNSCREW ANY OF THE SCREWS AT THE NECK OF THE TUBE.
TAMPERING WITH THESE SCREWS WILL VOID WARRANTY.
Caution
This device produces HIGH VOLTAGE when energized. To be operated only by qualified personnel.
The Mini-X-OEM contains a high voltage power supply. High voltage is not exposed but the unit
should be grounded as a precaution. It should be mounted to a metal fixture via the provided brackets.
The high voltage power supply has been thoroughly tested and should not ever arc to its own case.
However, if at any time any high voltage arcing or popping is heard, immediately discontinue use. High
voltage arcing has a distinctive sharp cracking sound. Contact sales ([e-mail]) if you suspect
that the power supply is arcing.
1.2 Radiation
The Mini-X-OEM product is intended to generate X-ray radiation during normal operation. It has
been designed to focus radiation in the designated output direction, but radiation can be scattered in
other directions and should be addressed with shielding and/or monitoring in the final application.
Caution
This device produces X-RAYS when energized.
To be operated only by qualified personnel.
Radiation levels external to the X-ray tube housing with the brass safety plug ON do not exceed 2.5
mrem/h measured 5 cm from the surface of the housing in accordance with Requirements 5.2.2.1.1 and
5.2.2.2.2 of the NBS Handbook for Radiation Safety for X-Ray Diffraction and Fluorescence Analysis
Equipment. For more information please see http://epswww.unm.edu/xrd/nbs111.pdf .
1.3 Beryllium Window
When unpacking the Mini-X-OEM pay careful attention to the Beryllium (Be) window on the front of
the unit. This is a fragile window which can be damaged by impact. Beryllium (silver/gray and metallic)
and beryllium oxide dust (normally a whitish powder) are harmful if inhaled or ingested.
AVOID ALL CONTACT WITH THIS PART OF THE X-RAY TUBE.

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1.4 Heat and Temperature
The ambient temperature surrounding the X-ray tube must not exceed 50 oC. Improper cooling is
the single highest cause of X-ray tube failures and is not covered under the Mini-X-OEM Warranty. It is
the user’s responsibility to provide an adequate cooling system for the Mini-X-OEM.
1.5 Prop65 Warning
WARNING
This product contains the following chemicals, which are known to the State of California to cause
cancer, birth defects or other reproductive harm if exposed to them through improper use, storage, or
disposal of the product:
Prop 65 Chemical
Type of Toxicity
CAS No.
Product part containing
the chemical
Beryllium
Cancer
--
Detector window
Please consult this owner’s manual for proper use, storage, care and disposal of the product. For
more information, go to: www.p65warnings.ca.gov
2Introduction
Important –Read the precautions in Section 1 of this manual before operating this equipment.
2.1 Description of Mini-X-OEM and MX-50 Controller
The Mini-X-OEM is a precision x-ray generator designed for applications that require small size and
low power consumption. The source includes a miniature sealed x-ray tube with a transmission-type end
window and a high voltage power supply encapsulated in a single radiation-shielded unit. The source is
designed specifically to be used as a component of a bench-top or hand-held x-ray spectrometer for the
detection of trace elements using x-ray fluorescence spectrometry.
The Mini-X-OEM differs from the Amptek Mini-X. The Mini-X has a USB interface to control the
voltage and current through PC software and makes it easy to set up XRF experiments. The Mini-X-OEM
version is controlled by the end user, by supplying analog voltages to control the voltage and current of
the tube. This is the preferred method in table-top and hand-held OEM applications where all the
functions of the instrument are controlled by a single internal computer. The MX-50 Controller includes
the interface circuitry found in the Mini-X: it includes a USB interface to generate the necessary control
voltages. A block diagram of the complete system is shown below.

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The Mini-X-OEM has been designed to simplify the XRF process by providing a grounded anode,
variable current and voltage controlled via USB and ease of operation. It features a 50 kV/80 µA power
supply, a gold (Au), silver (Ag), rhodium (Rh), or tungsten (W) transmission target, and a beryllium end
window. A collimator and various filters are also provided.
The MX-50 family of products are controllers designed to interface with miniature X-ray tubes and
HVPS modules, including Amptek’s Mini-X-OEM. The MX-50 family has a USB interface to produce the
voltages to control the voltage and current in the X-ray tube. Software running on the PC controls the
tube. The MX-50 also includes a safety interlock circuit and controls for a warning light.
2.2 Options and Variations
Anode material
The Mini-X is available with one of four anode materials: silver (Ag), gold (Au), rhodium (Rh), and
tungsten (W).
MX-50 Controllers
There are three different variants of the MX-50 currently available. These differ in the allowable
range of control voltages for voltage, current, and power and match the specification of modules supplied
by Newton Scientific. The MX-50 is suitable for the 50 kV, 4W monoblock. The MX-50.10 is suitable for
the 50 kV, 10W monoblock. The MX-70 is suitable for the 70 kV, 10W monoblock unit.
The MX-50 contains hardware jumpers which indicate, to the processing software, the configuration
(50 kV, 4W; 50 kV, 10W; 70 kV, 10W). It is critical that one use the correct MX-50 configuration for the
tube. If one mixes these up, the tube will be operated at the incorrect voltage and current and the power
max exceed the absolute maximum, thus damaging the tube.
3Specifications
3.1 Mini-X-OEM Specification table
Silver (Ag) Target
Gold (Au) Target
Rhodium (Rh) target
Tungsten (W) target
Target Thickness
0.75 μm (±0.1 µm)
1 μm (±0.1 µm)
0.75 μm (±0.1 µm)
1 μm (±0.1 µm)
Tube Voltage
10 kV to 50 kV
Tube Current
5 µA to 200 µA max.
Approximate Dose
Rate
1 Sv/h @ 30 cm on
axis, 50 kV and 80 µA
1.3 Sv/h @ 30 cm on
axis, 50 kV and 80 µA
1 Sv/h @ 30 cm on
axis, 50 kV and 80 µA
1.3 Sv/h @ 30 cm on
axis, 50 kV and 80 µA

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Approximate Flux
106counts per
second/mm2on the
axis at a distance of
30 cm (50 keV/1 µA)
1.3x106counts per
second/mm2on the
axis at a distance of
30 cm (50 keV/1 µA)
106counts per
second/mm2on the
axis at a distance of 30
cm (50 keV/1 µA)
1.3x106counts per
second/mm2on the
axis at a distance of
30 cm (50 keV/1 µA)
Continuous Power
4 W max. @ 100% duty cycle
Window Material
Beryllium (Be); window at ground
Window Thickness
127 µm
Focal Spot Size
Approximately 2 mm
Output Cone Angle
120°
Cooling
Air cooled
High Voltage
Stability
< 0.1%
Leakage Radiation
<5 µSv/h (0.5 mrem/h) at 5 cm with safety plug installed
Power Consumption
9 W at 50 kV and 80 µA
Input Voltage
6 to 12 VDC
Setting Time
Typical < 1 s
Weight
360 g
Humidity
30 to 90% non-condensing
Operating Temp
-10 °C to +50 °C
Storage Tempe
-25 °C to +60 °C
Warranty
One year or 2000 hours, whichever comes first
Figure 2. Mini-X Isopower. The current and voltage must be set in accordance with this curve or the Mini-
X may be severely damaged. Damage of this kind is not covered under warranty. Amptek’s control
software limits the power to this curve. If one commands the system to a power exceeding the power
limit, the software will use the commanded HV and rollback the current to meet the power limit.

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3.2 MX-50 Specification table
Power Consumption
Up to 20 W
Input Voltage
12 VDC (AC adapter included)
Control
USB, mini-USB connector (cable included)
Setting Time
Typical < 1 s
Weight
360 g
Humidity
30 to 90% non-condensing
Operating Temperature
-10 °C to +50 °C
Storage Temperature
-25 °C to +60 °C
3.3 Output X-Ray Spectra
Figure 3. Output Spectrum with silver (Ag) target (left) and gold (Au) target (right). These were measured
using a 1 mm thick CdTe detector located 1 meter from the Mini-X with a 1 mm pinhole collimator (made
from tungsten) in front of the detector.
Mini-X Silver (Ag) X-Ray Tube Output Spectrum
0 5 10 15 20 25 30 35 40 45 50 55
Energy (keV)
Counts
Log
Linear
Ag Ka
Ag Kb
Mini-X Gold (Au) X-Ray Tube Output Spectrum
0 5 10 15 20 25 30 35 40 45 50 55
Energy (keV)
Counts
Log
Linear
Au La
Au Lb
Au Lg

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4Mechanical Interface
4.1 Dimensions
Figure 4. Mini-X-OEM mechanical dimensions in inches [mm].
Figure 5. Brass cover dimensions (in mils/mm). This holds the safety plug or collimators and filters.
4.2 Mini-X-OEM Connector
See section 4.1 for drawing and pinout.
10 Positions Header, Shrouded Connector 0.100" (2.54mm)
Sample mating connector: 3M P/N 89110-0101, 10 Position IDC Socket
Pin #
Name
Type

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1
V+
PWR, 6 to 12 VDC
2
V+
PWR, 6 to 12 VDC
3
GND
GND
4
GND
GND
5
TUBE I CONTROL
ANALOG IN, 0 to 4 VDC
6
TUBE HV CONTROL
ANALOG IN, 0 to 4 VDC
7
TUBE READY
DIGITAL OUT, TTL
8
TUBE ENABLE
DIGITAL IN, TTL
9
TUBE HV MONITOR
ANALOG OUT, 0 to 4 VDC
10
TUBE I MONITOR
ANALOG OUT, 0 to 4 VDC
4.3 MX-50 Connectors
Figure 6. Front (left) and rear (right) connector panels of the MX-50.
Front panel Mini-X-OEM
Connector and pinout match that in section 4.2 for the Mini-X-OEM.
See section 5.1 for the voltages for the MX-50 variants.
Pin 1
Pin 10

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Power
Power Jack on MX-50: Hirose MQ172-3PA(55).
Mating Plug: MQ172-3SA-CV
Pin #
Name
2
Do Not Connect
3
GND
1
VIN (+12 V DC)
Interlock
OST, EDSTLZ1550/4
Mating Plug: OST, EDZ1550/4
Pin #
Name
1
PWR to interlock
2
PWR from interlock to HVPS
3
Q1 DRAIN
4
GND
The function of the interlock is described in section 5.2.
USB
Standard USB ‘mini-B’ jack.
4.4 Mounting
The Mini-X-OEM can be fastened using the mounting holes and brackets that are provided.
4.5 Cooling
The Mini-X-OEM requires proper and adequate cooling for maximum life. As such, it is the user’s
responsibility to provide a cooling design, such that the ambient temperature of the X-ray tube does not
exceed 50 oC. Air cooling via a small fan is recommended. Improper cooling is the single highest cause of
X-ray tube failures. Improper cooling is not covered under the warranty.
Figure 7. Temperature sensors. The maximum operating temperature of the Mini-X is 50 oC. The
Temperature Sensors in this example show the Mini-X exceeded 54 oC.
This voids warranty.
Dark circles
indicate
operating
temp >54 °C

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5Electrical Interface
5.1 Power Interface
Nominal input voltage 6 to 12 VDC
Absolute Maximum Power Supply Voltage +12.5 VDC
Absolute Minimum Power Supply Voltage + 6.0 VDC
Input power outside this range will damage Mini-X-OEM components.
5.2 MX-50 Voltages
PIN
NAME
MX-50
MX50.10
MX-70
1
V+
12 VDC
2
V+
12 VDC
3
GND
GND
4
GND
GND
5
TUBE I CONTROL
0.1 - 4 V →5 - 200 µA
0.1 - 4 V →5 - 200 µA
0 - 3 V →0 - 150 µA
6
TUBE HV CONTROL
0.4 - 4 V →5 - 50 kV
0.4 - 4 V →5 - 50 kV
1.8 - 3.5 V →35 - 70 kV
7
TUBE READY
Low=Not Ready, High=Ready
8
TUBE ENABLE
Low = Off, High = Enable
9
TUBE HV MONITOR
0.4 - 4 V →5 - 50 kV
0.4 - 4 V →5 - 50 kV
1.8 - 3.5 V →35 - 70 kV
10
TUBE I MONITOR
0.1 - 4 V →5 - 200 µA
0.1 - 4 V →5 - 200 µA
0 - 3 V →0 - 150 µA
Power
4 W
10 W
10 W
5.3 MX-50 Interlock
The MX-50 has a hardware interlock in order to prevent accidental radiation exposure. This interlock
must be shorted (enabled) in order for the Mini-X to produce X-rays. The left figure below shows the
interlock disabled. The Mini-X will not produce X-rays in this configuration. The right figure shows the
interlock enabled. The Mini-X will produce X-rays in this configuration. Always store with the interlock
disabled when not in use.
Figure 8. Interlock disabled (left) and enabled (right).
1
2 3
1 2 3 4
1
2 3
1 2 3 4
J
1
J
1
J
3
J
3

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One of the primary purposes of the interlock is so that the user can interface to external safety
mechanisms. This is most commonly implemented as a shutter or cover that, when opened, disables the
interlock and stops the generation of X-rays. When the tube is producing X-rays and the interlock is
disabled, the tube will go into a reset mode. It is therefore necessary to restart the tube through software.
Re-enabling the interlock after disabling it will not resume the production of X-rays.
The figure below is a block diagram of the MX-50 power and control interface, illustrating the use of
the “Interlock” connector. This connector has two functions: it permits the user to implement a safety
interlock, which turns off the X-ray tube when a switch is opened, and it permits the user to implement
an external indicator to show when the tube is in use.
Figure 9. Block diagram of the MX-50 power and control interface.
As shown in the figure, power is supplied to the high voltage power supply (HVPS) via a connection
between pins 1 and 2 of the interlock connector. If the connection between these pins is interrupted,
there is no power to the HVPS and so the tube turns off. In addition, this latches a bit in the monitor
circuit, which must be reset via a USB command. When a connection is restored between pins 1 and 2,
although power is restored to the HVPS, the unit is not turned on until this command is received. The
voltage at pins 1 and 2 is typically 12 VDC. As shown in the figure, a user could connect this to a switch,
typically located on the cover of the enclosure housing the X-ray target. If a user accidentally opens the
cover without first turning off the tube, this will automatically turn off the power, preventing accidental
radiation exposure.
The MX-50 contains a speaker and an LED, both of which indicate that the X-ray tube is turned on.
The LED is visible on the back side of the MX-50 package, but in some applications the Mini-X-OEM and
MX-50 is inside an enclosure. Pins 3 and 4 can be used to drive an external indicator, such as the LED
sketched above. The user must provide the circuit interfacing to pins 3 and 4. Q1 is an N-channel
enhancement mode MOSFET, part number ZXM61N02FTA. Key ratings are VDSS=20V (absolute max) and
ID=1.7A (absolute max at 25 oC).
6MX-50 Software Interface
6.1 Software Installation
Installing USB Drivers
If your computer is on the Internet, and your settings do not prevent updating, then the USB drivers
will be automatically downloaded using Windows Update.

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1. Connect the MX-50 to the PC via a Mini USB Cable. Plug the MX-50 12 VDC supply into a 110/200
VAC outlet and into the Mini-X-OEM back panel.
2. A “Found New Hardware” or “Installing Device Driver” box opens. Follow any instructions for
“Automatic” installation over Windows Update (the detailed instructions will vary with the
operating system).
3. If the driver has been successfully installed, it will be visible in Device Manager, as shown below.
Figure 10. The Mini-X will appear in Devices.
If your computer is not on the Internet or your Firewall or Administrative settings prevent automatic
installation, then you will need to install the drivers manually. The drivers are on the installation CD and
can be downloaded from Amptek’s website. Go to the "Mini-X Drivers" directory and run the appropriate
"dpinst" file for your OS.
Installing Application Software
1. Locate the “Mini-X Software/Mini-X Setup” folder on the Amptek Installation CD or download
from Amptek’s website.
2. Right click the Mini-X_Controller_Setup.exe file and select “Run as Administrator” and follow the
instructions.
Figure 11. Mini-X setup.

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6.2 Operating the Mini-X-OEM with MX-50
X-rays exit the Mini-X-OEM in a 120ocone. NOTE: When using the 2 mm
collimator, the X-ray cone is 5°.
SAFETY PRECAUTIONS MUST BE USED FOR EQUIPMENT THAT
PRODUCE X-RAYS.
MINIMIZE HUMAN EXPOSURE TO X-RAYS.
USE A GEIGER COUNTER TO MONITOR RADIATION.
STOP: ONLY QUALIFIED PERSONNEL SHOULD PROCEED BEYOND
THIS POINT.
1. Install the software as described in Section 5.1.
2. Connect the Mini-X-OEM to the PC computer with the USB cable.
3. Connect the AC power adapter to the Mini-X-OEM and plug it into
an appropriate 110/220 AC power outlet.
4. Remove the safety plug from the cover attached to the Mini-X-OEM. Either install the collimator
into the cover or leave the cover empty. Re-attach the cover to the Mini-X-OEM.
5. Make sure that you have verified the anticipated direction of the X-ray beam as described above.
6. The MX-50 has a hardware interlock in order to prevent accidental exposure. This interlock must
be shorted (enabled) to produce X-rays. Install the interlock plug to produce X-rays.
7. Open the Amptek Mini-X Controller Software. It will appear as below.
Figure 13.
8. Click the Start Amptek Mini-X button. The software will display the serial number of the MX-50.
Figure 12.
Figure 7. Output X-Ray
cone.

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Figure 14.
9. The software defaults to a setting of 15 kV and 15 A. To change the values click into the
appropriate text box and type in the desired number.
IMPORTANT: Do not enter a voltage higher than is rated for your unit. In addition, the total power
is governed by the Isopower curve. Do not enter a current that exceeds the indicated value for
that voltage. If a requested current is too high, the software will automatically adjust it to the
maximum allowed value.
10. Click the HV ON button to turn on the tube. The software will ask you to confirm. Click Yes.
THE MINI-X IS NOW PRODUCING X-RAYS
11. The Mini-X-OEM will start to beep and the red LED on the end panel of the unit will flash. In
addition the yellow and black “Radiation Symbol” will blink in the Mini-X Software and the words
“X-Ray ON” will appear.
Figure 15.
12. The Voltage and Current monitors now show the actual X-ray tube condition. Although the values
for Voltage and Current might be slightly different from the requested values, these are the actual
values of the tube.
13. To change the high voltage and current, click into the appropriate text box and enter the number.
Then click the Set High Voltage and Current button.

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14. To turn off the Mini-X-OEM click the HV OFF button, then click the Exit button to exit the software.
Always unplug the Mini-X-OEM, install the safety plug, and disable the interlock when not in use.
7Mini-X-OEM Design
7.1 X-ray tube
The heart of the Mini-X-OEM is a compact X-ray tube which uses a transmission target. The high
voltage power supply (HVPS) produces a bias voltage between the target (which is grounded) and the
filament. This voltage accelerates electrons produced at the filament into the target. When these
electrons decelerate in the target material, they produce bremsstrahlung radiation, X-rays with a
continuous energy spectrum. They also produce X-rays at the characteristic energy of the target material.
Many of these X-rays are directed towards the window, made of Be (beryllium), where they can be
collimated into the sample. The X-ray tube contains shielding which stops X-rays outside of the 120ocone.
7.2 High Voltage Power Supply
The HVPS takes the 12 VDC input and steps it up to the commanded bias (10V to 50V). It is a switch
mode regulator with a conventional Cockcroft-Walton multiplier, operating between 40 and 100 kHz.
There are three inputs to the HVPS: an analog voltage which sets the HV, an analog voltage which
sets the current, and an ON/OFF logic signal. The HV and current signals have a range of 0 to 4V, which
correspond to the HPVS settings: a 2V input to the HV results in a half-scale output of 25 kV.
There are three outputs from the HVPS: an analog voltage reading the HV, an analog voltage reading
the current, and a STATUS logic signal. These have the same scale factors as the inputs.
7.3 MX-50 Control and Interface Module
The control module takes the control values commanded via USB and uses these to set the proper
control voltages and to send the ON/OFF command. It also reads the outputs. There are a few key details
to the control and interface module:
oThe interlock circuit is very important, both for radiation safety and for successful operation of
the Mini-X-OEM. Please refer to sections 4.2 and 8.2 for details.
oThe software compares the commanded values for HV and current to the outputs. If the inputs
and outputs differ (outside of tolerance limits and sustained for a certain time), the HVPS is
disabled.
8Mini-X-OEM Accessories
8.1 Collimator
The Mini-X is provided with two collimators to facilitate its use in XRF applications. They consist of
brass collimators with aluminum (Al) inserts and a cover that screws into the Mini-X-OEM. The collimators
have 1 and 2 mm diameter holes. A brass safety plug is also provided which, when installed, reduces the
flux from an operating tube to less than 25 µSv/h (2.5 mrem/hr) at 5 cm away in accordance with
Requirements 5.2.2.1.1 and 5.2.2.2.2 of the NS Handbook for Radiation Safety for X-Ray Diffraction and
Fluorescence Analysis Equipment. Insert the collimator into the cover and then carefully screw the
assembly onto the Mini-X-OEM. The collimator has a 2 mm diameter hole.

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Figure 16. Left photo shows the Mini-X-OEM collimators, safety plug, and cover. The middle photo shows
the safety plug installed in the cover and attached to the Mini-X-OEM. This configuration meets the
radiation requirements discussed above. The Mini-X-OEM ships from the factory in this configuration. The
right photo shows the collimator installed in the cover.
8.2 Brass Safety Plug
When the brass safety plug is installed in the cover (figure 16, middle) and screwed onto the Mini-X-
OEM it meets the radiation safety requirements of Section 1.2. For personal protection always install the
safety plug into the cover and attach to the Mini-X-OEM when not in use. The Mini-X-OEM ships from the
factory in this configuration.
8.3 Filters
The Mini-X-OEM is shipped with a set of filters to modify the output spectrum of the tube to better
suit a particular application. The use of any filter will reduce the flux, so the current may have to be
increased to obtain an appropriate flux. Install the filter at the Mini-X screw base. Then screw on the
cover with the collimator. Make sure that the cover screws all the way down, otherwise radiation will
leak through the gap. All filter thicknesses will fit except for the 40 mil Al. This filter must be installed on
the outside output aperture of the collimator and held in place with the black cap provided.
Filters are very important for obtaining high quality results in XRF analysis. Please refer to Amptek’s
application note, “X-ray Tube Filters FAQ”, for more information.
Material
Thickness
m/mils
#
Included
Al
1016 / 40
5
Al
254 / 10
5
Cu
25.4 / 1
3
Mo
25.4 / 1
2
Ag
25.4 / 1
1
W
25.4 / 1
1
Figure 17. Filtered output spectra.

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9Radiation Levels and Example Shielding
Radiation levels external to the X-ray tube housing with the brass safety plug ON do not exceed 25
µSv/h (2.5 mrem/h) measured 5 cm from the surface of the housing in accordance with Requirements
5.2.2.1.1 and 5.2.2.2.2 of the National Bureau of Standards (NBS) Handbook for Radiation Safety for X-Ray
Diffraction and Fluorescence Analysis Equipment. For more information please see the NBS Handbook.
Examples of Shielding (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 the shielding material.
CAUTION: The Mini-X-OEM is only one component of an X-ray instrument. It is the responsibility of the
user, the OEM customer, or experimenter to provide a fail-safe metal enclosure to prevent escaping
radiation while using this product. The final product (turn-key system) must comply with local government
regulations to protect personnel from exposure to radiation. Amptek Inc. bears no responsibility for the
incorrect use of this product.
10 Understanding the Interlock and Alarm
Safety is an important consideration with the Mini-X-OEM X-ray tube. Two key elements in the safety
system include the interlock and the alarm (the light and the beeper).
The Mini-X includes three main components: (a) the X-ray tube, (b) a High Voltage power supply
(HVPS) and (c) the control and monitor circuit. The interface between the high voltage power supply and
the control circuit is critical to understanding the interlock system. Shown below is a schematic which
shows the connection between the control/monitor circuit and the HVPS, the interlock, and the alarm.
J4 connects the control/monitor circuit and the HVPS. Pins 1 and 2 carry the power (12 VDC) to the
HVPS. Pins 3 and 4 are ground. Pins 5 and 6 are analog signals, inputs to the HVPS which set the current
and HV bias respectively. They are produced by DACs in the control and monitor circuit. Pins 7 and 8 are
logic signals; pin 7 is an output from the HVPS indicating that it is functioning properly while pin 8 is an
enable to the HVPS. Pins 9 and 10 are analog signals, output from the HVPS indicating the HV bias and
current respectively.
For the HVPS to turn on there must be power on the power pins, valid voltages on the analog control
lines, and the logic enabled. The HVPS then produces three outputs read by the monitor circuit. Key
issues for the safety interlock are the following:
1) The interlock is the connection between pins 1 and 2 of J3. This connection carries the 12 VDC
power supply current to the HV supply. If the interlock is opened, the HV supply is powered off
so cannot operate. This is important because it guarantees that the HVPS will turn off when the
interlock is opened: there is no other path to supply power to the HVPS.
Note that the interlock carries the full supply current, so long wires are not recommended.
If the interlock will be operated from a remote switch, we recommend having the switch operate
a relay located close to the Mini-X.

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Note also that these pins can provide the power to the HVPS and to the monitor/control
circuits. For customers who do not want to use the AC/DC supply provided by Amptek, these pins
on J3 may be used as an alternate power supply connection. Note that the input power is 12 VDC
and must go to both pins 1 and 2 (pin 2 supplies the HVPS while pin 1 supplies the control circuits).
Note also that the user is then responsible for the interlock circuitry.
2) If the interlock is opened, U3 is held low, generating the /RESET signal. This signal resets the
two DACs used to control the HV and current. These DACs, P/N AD5623, go to zero volts when
reset and latch the zero voltage. The Mini-X requires a command be sent over the USB interface
to set these to a non-zero voltage.
This is important because this prevents the HVPS from turning back on as soon as power is
restored. When the interlock is restored, power is restored to the HV supply but the control
inputs are still at zero volts. A command must be sent after the interlock is restored to produce
X-rays. This ensures a redundant sequence for turning on X-rays: a hardware switch must be
closed and a software command must be issued.
The schematic also shows the how the alarm functions. When the controller brings the control line
high, it activates the two 555 timers. One produces a 1.6 Hz signal, the other a 5 kHz signal. These signals
control the speaker and the LED on the Mini-X: the LED flashes at 1.6 Hz, and the speaker produces a 5
kHz tone, modulated at 1.6 Hz. Please note that there is no heat-sinking on the FET so it cannot dissipate
significant continuous current.

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Figure 18. Schematic of the interlock and alarm portion of the Mini-X Control and Monitor circuitry.