Here is a list of parameters to be implemented by the GSI group
Each part with a list of possible parameters to be controlled by the program
1. Gas cell (Munich?)
In the gas cell the ions are stopped by collisions with the noble gas. The ions are brought to
the exit of the chamber with the gas flow and an additional electrical field.
a) pressure
b) dc voltages for extraction
c) interrupt from gas purification
2. Extraction (Munich?)
The ions are now guided by a radio frequency field out of the high pressure region.
a) radio frequency
i. frequency
ii. amplitude
iii. phase to buncher rf ?
b) dc voltages
c) pressure
3. Buncher
The dc ion beam is accumulated in the linear Paul trap and cooled for a defined time by
collisions with the noble gas. A bunch of ions will be extracted.
a) radio frequency
i. frequency
ii. amplitude
iii. phase to extraction rf ?
b) dc voltages
c) capture pulse
i. time
ii. duration
iii. amplitude
d) ejection pulse
i. time
ii. duration
iii. amplitude
e) pressure
4. Purification
After the flight time to the purification trap, this Penning trap opens, lets the ions in and closes
again. Only one specific isotope will be centered by the applied rf and cooled to room
temperature, all other kinds will go to the trap wall. Then the ions are ejected.
a) radio frequency (c)
i. frequency
ii. amplitude
b) dc voltages
c) capture pulse
i. time
ii. duration
iii. amplitude
d) ejection pulse
i. time
ii. duration
iii. amplitude
e) ejection ramp ?
f) pressure
5. Mass
The precision mass measurement will be the first experiment on SHIPTRAP. It is built within
the beamline of SHIPTRAP. The ion motion is excited by an rf-field, the ions carefully
ejected and the time of flight from trap to the detector is measured.
a) radio frequency (c)
i. frequency
ii. amplitude
b) radio frequency (or )
i. frequency
ii. amplitude
c) dc voltages
d) capture pulse
i. time
ii. duration
iii. amplitude
e) ejection ramp ?
f) ejection pulse
i. time
ii. duration
iii. amplitude
g) pressure (interrupt)
6. Beam Transport
ion optics (drift tubes, deflectors, lenses)
All these parameters have to be preset (or checked) for a measurement. To get the optimum
parameters for beam transport and purification (and to measure the masses) all parameters
have to be scannable (changed step by step in a defined interval, repeatedly). A possibility for
2-dimensional scan is wanted.
7. Detectors
In additional the program has to control and read out the detectors:
1. after gas cell ?
2. after buncher
3. after Penning traps
At all places the count rate is the important value.
To determine the cyclotron frequencies in the purification (for cooling) and the mass trap at
detector 3 there is also the time of flight from purification and mass trap to be recorded.
General Aspects
Data saving
The data (TOF spectra) have to be saved after each measurement step.
To identify the measurement conditions, all parameters shall be stored with the data.
Possible interrupts should be stored as well.
The data are always stored. If not a specific file name is chosen, a predefined is used.
Program surface
The user can set all values from the program and has at all times the possibility to check these
parameters.
The count rate, TOF spectra, possible fits ... are displayed. It might be good, to be able to
select the displayed windows. The window size might be adjustable. A print out of a window
must be possible.
There should be the possibility to have predefined sets of parameters/scan function for
different tasks.
Remote control should be possible.
The buncher and the Penning traps should run independently. A possibility for simultaneous
run should be sought for.
Safety aspects
The dc voltages and other fixed parameters might be checked now and then.
In case of vacuum failure the high voltage has to be switched of and the pumps should react in
a definite way (same for total power failure).
Hardware
1. Gas cell (München)
a)
b)
c)
pressure
dc voltages for extraction
interrupt from gas purification
2. Extraction
a) HP
b) iseg
c)
radio frequency
dc voltages
pressure
3. Buncher
a) DS345
b) iseg
c)
d)
e)
radio frequency
dc voltages
capture pulse
ejection pulse
pressure
4. Purification
a) DS345
b) iseg
c)
d)
e)
f)
radio frequency (c)
dc voltages
capture pulse
ejection pulse
ejection ramp ?
pressure
5. Mass
a)
b)
c) iseg
d)
e)
f)
g)
radio frequency (c)
radio frequency (or )
dc voltages
capture pulse
ejection ramp ?
ejection pulse
pressure (interrupt)
6. Time Structure
PPG100
7. Detectors/Acquisition
a) ?
b) MicroSpherePlates/CCD-Camera
c) MicroChannelPlates??/MultiChannelScaler
8. Computer
a) Control PC (remote)
i. Ethernet
ii.
a) Measurement PC (local)
i. Ethernet
ii. GPIB (rf, MCS)
iii. CAN (dc)
iv. RS232 (pressure control)
v. ISA (Pattern Generator)