Monochromatic beam attenuators are located in the experimental hutch just after the safety shutter and the wall separating the experimental and optic hutch. They are mounted on a yellow steel support bolted to the floor to avoid vibrational problems.

 ID23_eh1_monoatt_photo.gif

 

To access all possible rates of beam attenuation, there are in fact three sets of four different foils made of Aluminium or Carbon with different thickness. These foils are mounted on a stainless steel support and a pneumatic cylinder remotely controled to put the attenuators in and out. The vacuum inside the chamber is about mbar pressure due to the fact that the vacuum pump have been transfered outside the hutch to avoid vibrations.

monoattschema.gif (Monochromatic Beam Attenuator Schema)

 

The attenuation factor is depending of the material (Carbon or Aluminium), thickness but also of the insident beam Energy. Follows the table of foil thickness in the three different sets of attenuators: 

 

 
Aluminium
Carbon
Set
3
 
2
 
1
Position
4
3
2
1
 
4
3
2
1
 
4
3
2
1
Thickness in mm
4.00
2.00
1.00
0.50
 
0.25
0.10
3.50
1.80
 
0.80
0.50
0.20
0.10