Ultra-thin AP3 X-ray Windows
AP3 ultra-thin polymer windows are the established standard for performing x-ray windows for low energy x-ray analysis. AP3 windows are ideal for applications that require maximum transmission of low energy x-rays, high mechanical strength, light rejection, vacuum tightness, and reliability. AP3 windows are used in applications where high temperature, light element detection is important and beryllium windows are ineffective (see Figure 1).
Applications
X-ray Detectors
■ Silicon Drift Detectors (SDD) ■ Si(Li) Detectors ■ Si-PIN Detectors
Features
Benefits
Ultra-thin polymer film
Maximum transmission of low energy x-rays
Thin aluminum coating
Charge dissipation
UV, IR and visible light rejection
DuraCoat®
Corrosion resistant, hermetic seal
Silicon support structure
High mechanical strength, durable
High purity
Minimal spectral contamination
Uniform thickness
Consistent transmission across entire window
Window Specifications
Open Area:
77%
Helium Leak Rate:
<1x10-10 mbar • L/s†
Max. Temp. (1 atm Differential):
40°C
Max. Temp.(Zero Pressure Differential):
70°C
Front Pressure Limit (Atmosphere Side):
2atm
Back Pressure Limit (Vacuum Side):
1atm
† See “Light Rejection and Vacuum Tightness” section below
Light Rejection and Vacuum Tightness
AP3 windows provide good rejection of UV, IR, and visible light. AP3 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. 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. Depending on mount geometry test conditions may need to be adjusted.
Window Composition
AP3 windows are composed of ultra-thin layers of polymer, DuraCoat®, and aluminum. AP3 windows are supported by a silicon support structure designed to add support for the film at a minimal profile (open area = 77%). Moxtek® attaches each window to a mount using vacuum compatible epoxy adhesive.
Mechanical Strength
AP3 windows are supported by a rigid silicon grid with 77% open area. This patented window design enables the AP3 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 of AP3 Windows
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
FIgure 1 X-ray Transmission, Film and Grid
Figure 1 X-ray Transmisson of AP3 and AP5 Windows