Ultra-thin AP5 X-ray Windows
AP5 ultra-thin polymer windows are the highest performing x-ray windows available for low and high energy x-ray analysis. AP5 windows are ideal for applications that require maximum transmission of low energy x-rays, high mechanical strength, light rejection, vacuum tightness, reliability, and increased solid angle. AP5 windows are used in applications where high temperature, light element detection is important and beryllium windows are ineffff ective (see Figure 1 and 2). AP5 windows are similar in application to AP3 windows but are designed to work for detectors larger than 100mm2 where AP3 windows are too small.
Applications
X-ray Detectors
■ Silicon Drift Detectors (SDD)
■ Si(Li) Detectors
■ Si-PIN Detectors
Features
Benefifits
Ultra-thin polymer film
Maximum transmission of low energy x-rays
Thin multi-layer coating
Charge dissipation
UV, IR and visible light rejection
Corrosion resistant, hermetic seal
Carbon support structure
High mechanical strength, durable
Improved x-ray transmission
Unique design geometries possible
High purity
Minimal spectral contamination
Uniform thickness
Consistent transmission across entire window
Window Specififi cations
Open Area:
78%
Helium Leak Rate:
<1x10-10 mbar • L/s‡
Max. Temp. (1 atm Diff erential):
40°C
Max. Temp.(Zero Pressure Diff erential):
70°C
Front Pressure Limit (Atmosphere Side):
2 atm
Back Pressure Limit (Vacuum Side):
0.5 atm
‡ See “Light Rejection and Vacuum Tightness” section below
Light Rejection and Vacuum Tightness
AP5 windows provide good rejection of UV, IR, and visible light. AP5 windows also provide a hermetic barrier to gases. Every window is tested and is guaranteed to have a leak rate of less than 1 x 10-10 mbar ● L/s of helium. The helium leak rate is tested by exposing the parts to a minimum of 0.5 SCFH helium sprayed immediately above and around the window on a calibrated helium leak detector for a minimum of 30 seconds. Test conditions may need to be adjusted depending on mount geometry.
Window Composition and Structure
AP5 windows are composed of ultra-thin layers of polymer, and other thin fifi lms with low Z compositions. AP5 windows are supported by a carbon support structure designed to add support for the fifi lm at a minimal profifi le with maximum open area and acceptance angle. Moxtek® attaches each window to a mount using vacuum compatible epoxy adhesive.
AP3
AP5
Thickness (μm)
380
265
Rib width (μm)
59
45
Opening width (μm)
190
190
Open Area %
76%
78%
Acceptance Angle
53°
72°
Mechanical Strength
AP5 windows are supported by a rigid carbon grid. This patented window design enables the AP5 window to survive over 10,000 cycles at room temperature and a differential pressure of 1.2atm with no degradation in window performance.
Table 1 Elemental X-ray Transmission
Atomic Number
Element
Transmission (Kα) (% of maximum)
AP3
AP5
14
Si
74%
73%
13
Al
75%
75%
12
Mg
72%
73%
11
Na
69%
69%
9
F
54%
54%
8
O
47%
47%
7
N
31%
31%
6
C
47%
49%
5
B
29%
23%
4
Be
9%
7%
Table 1 Elemental X-ray Transmission (Kα) of AP3 Windows
Acceptange Angle Graphic
X-ray Transmission, Composite Film and Grid
Figure 1 0-2 keV X-ray Transmisson of AP3 and AP5 Windows
Figure 2 0-25 keV X-ray Transmisson of AP3 and AP5 Windows