E 3 at Hahn-Meitner-Institute Berlin

Two Axis Powder Diffractometer with Multicounter

The powder diffractometer E3 is equipped with a position sensitive detector (multicounter). It is installed at the beam tube T2.

The diffractometer can be used to investigate the following metallurgical and crystallographic problems:

Instrument description
The diffractometer is equipped with a curved position sensitive BF3 - multicounter (400 cells) of 2Theta = 80° with a resolution of delta 2Theta = 0.2°, the usable 2Theta range is 3° - 115°. The detector shall be replaced by a new curved position sensitive ³He multicounter (1024 cells) of 2Theta = 80° with a resolution of 2 mm (delta 2Theta = 0.08°).

The 100 mm (in future 150 mm) high detector cells allow the integral measrement of the reflection profile and the detection of weak powder reflections or diffuse scattering contributions. A flexible choice of the wavelength between lambda = 0.9 Å and 3.6 Å is achieved by three vertically focusing monochromators and two fixed take-off angles.

The primary beam and its resolution is defined by a sapphire filter (reducing fast neutron contaminations), a removable graphite filter, two collimators (alpha1 = 10', 30') and the monochromator in use (see table). The local resolution of the measurements can be defined by automatically positioned primary and secondary diaphragms of adjustable geometry. Sample and detector installed on a "Tanzboden" are controlled by a VAX3200 workstation via CAMAC instrumentation.

Beam Tube for E3: T2
vertically focussing
Wavelengths at 2Theta
(in Å)
Monochromator crystal 42.5° 65°
Cu (220) 0.92 1.37
Ge (311) 1.22 1.84
HOPG (002) 2.40 3.6
neutron flux 2.3*106 n s-1 cm-2
(lambda = 2.4 Å, no collimation)
Collimations alpha1 = 10', 30'
alpha2 = 10', 15', 30'
maximal beam section
at sample position:
60 x 30 mm2
Detector present: curved position sensitive BF3 multicounter
in future: Curved position sensitive ³He multicounter
Radius 1500 mm
Channels 400 (in future 1024)
Angle Range (2Theta) 3° - 115° (detector width 80°)
Auxiliary equipment Eulerian cradle with integrated xyz translation device;
xyz translation device (400 kg);
high T oven (1200°C);
focusing mirror heating device (2000°C);