Blochdocs (March 2024)

Note

In January 2024 the receiver of the Carving manipulator on the A-endstation was rebuilt. It is now much sturdier and clamps more effectively, but the ability to make extra electrical contacts to the sample at a specific azimuth is no longer possible. See the ‘Carving’ pages for details.

Note

The B-endstation currently runs on an LN2 flow cryostat. The repaired closed cycle helium cryostat is expected to be back in operation by April.

Allowed EPU settings

Mode

EPU Phase

Allowed gap range (mm)

Allowed hv range (eV)

Horizontal

0

No restrictions

>10

Vertical

42

>15

>14

Circular +

0 .. 42

>18*

>15

Circular -

0 .. -42

>18*

>15

*Conservative estimate. To be verified.

Maximum countrate (A-endstation)

Excessive countrates will damage the MCP in the detector assembly, and at BLOCH it is very easy to generate unsafe countrates. Respect the following rules:

  1. Maximum 1 million counts per second if everything is in a narrow stripe (for example transmission mode or graphene’s Dirac cone)

  2. Maximum 10 million counts per second if intensity is evenly distributed across the detector

  3. Core levels should be measured in an angular lens mode, except where lens table limits make this impossible.

Warning

There is no background process in SES to monitor countrates, so you must verify that the countrate is safe while in voltage calibration mode. If you will perform an angle scan or photon energy scan, check the intensity over the whole scan range, not just your starting position. If you will measure in swept mode, ensure that the intensity slightly below your starting point is also safe.