1) Introduction: The
brehmstrahlung radiation can be used to characterize the quality of the
vacuum in a vacuum chamber and consequently to evaluate the
conditionning of such chambers.
The purpose of this device server is to calculate and to return the
signal and the background values of the Brehmstrahlung radiation
observed on a beamline during a scan. Those signals are obtained
from measurements taken by a beamloss detector during a scan of a XBPM.
2) Hardware: Three
equipments are required in order to perform a measurement:
- A XBPM motorization: This part is used to move the XBPM blades in
the radiation cone.
- A beamloss detector: This part measures the radiation level.
- The insertion devices installed on the considered beamline: They
are not driven, but a check is done before a scan because they must be in the open position.
3) Software:
- As a scan is a time consuming task (around 40 minutes for a scan)
it has been implemented as a thread which is created when the command "ScanStart" is issued..
- Three device servers are imported:
- The XBPM device server: It is in charge of the displacement of
the XBPM blades.
- The beamloss device server: It is the way to get the signal
value for each scan point.
- The Insertion Devices device server: It is used to get the
position of all the ID's installed on the considered beamline. A
position that is below 100mm disables the start of a scan.
- Main commands implemented:
- "ScanStart": This
command starts a scan by creating the dedicated thread. This command
can only be sent if the device is in the "STANDBY" state. When the scan
has started the state becomes "MOVING".
- "ScanAbort": This
command aborts a scan in progress. After this command is issued the
motorization is set to its initial position. This command can only be
sent if the device is in the "MOVING" state (a scan is in progress).
- "ScanGetResult":
Returns an array containing the scan positions and radiation values in
the following format:
Number of X points
|
Number of Z points
|
XPos[0]
|
ZPos[0]
|
Radiation value[0]
|
....
|
....
|
XPos[n]
|
ZPos[n]
|
Radiation value[n]
|
This command can be sent when the device is in the "STANDBY" state and
if a scan has been previously performed.
- "ScanGetSignalAndBackground":
This command returns an array containing the signal value at index 0
and the signal background at index 1 and fill the historical database
with the same values. This command can be sent when the device is in
the "STANDBY" state and if a scan has been previously performed. The
two values are calculated from the last scan datas.
