Figure
1 : Panoramic photo of new beam line as of Dec 23, 2013.
Spectrometer chamber and target 6-way cross not yet connected seen
to the left.
Figure
2 : Photo of new beam line connection to targer 6-way cross on Jan 24, 2014 showing also the change in the order of the beam line elements.
Figure
3: 3-D schematic of beam line design (Feb 2014) showing
quadrupoles, magnetic steerers, 1 set of 4-jaw slits (upstream
slits), turbo pump and beam profile monitor.
Figure
4: View of magnetic steerers (coils on beamline) and their
power supplies below them
Figure
5: Panoramic photo of new beam line as of May 2, 2014. Spectrometer
chamber and target 6-way cross now connected.
Figure
6: Photo of Beam Profile Monitor (BPM) controller box (down
just above NIM crate) and oscilloscope (top) viewer in Control Area
of Tandem.
Figure
7. Schematic of beam line vacuum components
Figure
8. Photo of the inside of the Beam Profile Monitor (BPM).
Visible on the left is the motor and shaft of the rotating wire.
The metal shield lining the inside of the beam line is connected
to the BPM signal. The curved rotating wire can be seen .
Figure
9. Photo of the image of the ion beam (optimized for highest
beam through the gas cell into FC2 of about 7nA with about 20nA
in FC1) on a home made phosphorus viewer hanging right under the
target gas cell. The image was estimated to be around 3 mm x 3
mm while the entry to our gas target cell is a hole of 2 mm diameter.
Improvement is clearly needed. The beam is 18 MeV C4+.
Slits 2 are wide open.
Figure
10. Same as Fig. 9 above, only now slits 2 have been set
at 3 mm x 3mm
Figure
11. Beamline distances between various elements. Details
of various parts can be seen in some of the previous figures.
Figure
12. Calibration formulas for the two ion beam bending magnets
at the Dimokritos tandem. I is the magnet current in Amps (A)
and f is the nmr frequency (only for the analyzing magnet). The
calibration constant kR[2] applies only to the APAPES
beam line at L45 (Red target area room).
Description of work package
Work Package
1
Start:
Month 1
Finish:
Month 15
Cost:
Title:
WP1:
Beam
line design and construction
Description:
Research Teams:
RT1, RT2, RT3
1.1 Optics design of complete
beam line
The optics of the entire accelerator will be checked with
the CPO code TRANSPORT and compared to real beam conditions.Then the optics of the new beam line will be designed
starting from the switching magnet port L45. This will determine
exactly what and where to place steerers, quadrupoles, beam
monitors, slits and the optimal length to the target for
highest transmission.
1.2 Beamline constructionUsing the optics design the new beam line will then
be constructed. This includes the beam tubing, support stands,
placing the focusing elements at the right place, adding
gate valves, pumping ports, vacuum gauges, etc.The machine shop will be used for many of the required
constructions. Materials needed for beam line and optical
elements already exist, but might need repairs.
1.3 Optical alignment
of new beam lineWill be performed with a telescope whose stand has
to be built and aligned with alignment mark at accelerator
switching magnet.
1.4
Vacuum test of new beam lineA turbo pump with fore line pump will be needed to
bring the beam line to a vacuum of 5Χ10-7 Torr
or better. If pumps not available they will have to be ordered
and bought.
1.5 Test new beam line
transmission with ions from TANDEMOnce under vacuum fluorine
or oxygen beams will be used to test beam line transmission
through slits by recording ion current at the end of the
beam line and comparing to current at switching magnet and
expectations of CPO TRANSPORT code.
Deliverables:
1
Report and possibly part of BS, MS or PhD thesis
WP1: Table of Activities in progress
Completed
Activity
Target Date
Ion Beam Optics study of L45
completed using MAD code (by N. Tsoupas)
Jan 2012
Tender for vacuum equipment
announced
Dec 2013
Order for vacuum equipment
placed
Feb 2013
Vaccuum equipment arrived
at Tandem lab
Jun 2013
O-rings and gaskets ordered
and received
Jul 2013
Set upstream slits on ion
optics axis (alignment)
SLITS1 Settings: Up
= 4.84, Down=2.65,
Left=3.80, Right=2.64
Dec 2013
L45 Beam line assembled,
optics elements placed in position, vacuum pumps installed,
Alignment slits and procedures checked, support structures
for chamber and target 6-way cross build, vacuum tests of
beam line and chamber succesful. Vacuum
attained1.3 x 10-7 Torr
in spectrometer chamber, 2.5 x 10-7
Torr in target 6-way cross, and 1.2
x 10-7 Torr in beam line before target valve.
Dec 2013
Connection of spectrometer
chamber and 6- way cross to beam line (Jan 24, 2014)
Jan 2014
Bought analog oscilloscope for beam profile monitor
Feb 2014
Tender for BPM controller
announced - ended unsuccessful
Feb 2014
Bought pneumatic Faraday cup
and magnetic steerer controller and power supplies
Feb 2014
Pneumatic Faraday cup installed
in front of 6-way cross
Feb 2014
L45 Dipole magnet power supplies
connected
Feb 2014
First
ion beam transmission test completed Feb 21, 2014 with
isolation valve closed, L45 dipoles on but L45 steerers off.
Measured 230nA in FC4 (before isolation valve) with 10 x 10
mm slits SL1 (after switcher but before the dipoles) and 400nA
in FC3 just before the switcher magnet. Beam: 1 MeV protons
Feb 2014
L45 Magnetic steerer power
supplied connected
Feb 2014
BPM controller and oscilloscope
connected to Tandem Control room area
Apr 2014
First ion beam transmission
test with isolation valve open, L45 dipoles on, L45 steerers
on all the way to last FC. [June 6, Used for
tests 2 MeV proton beam]
Jun 2014
First ion beam transmission
tests with heavy ions while measuring projectile Auger electrons (gas cell in) [July 23-30, 12 MeV C4+ beam (HE=4μA, Analyzed=70nA, FC2=3nA) ]
Jul 2014
BPM tests - BPM1 successful,
BMP2 noisy with no beam signal
Jul 2014
Wrote (AL+TZ) excel program
(SLITS-BEAM-ANGLE.xlsx) to test in a purely geometrical model
the effect of various aperture sizes of the slits and the gas
cell on the beam transmission and bkg.
Oct 2014
BPM2 tests and trouble shooting
to find source of noise and lack of signal. BPM2 removed and short found and repaired.
Oct 2014
Small bellows installed (when
BPM2 removed) between SLITS1 and quadrupole. Beam line was not
moved so SLITS1 settings assumed to be the same.
Oct 2014
BPM2 tests with proton beam,
exchanged preamps, moved oscilloscope and SSA5 unit to BPM2
- cable connection OK, preamps OK, finally also got BPM2 to
show signal with real beam after palying a bit with accelerator
optics on the HE end and after the analyzing magnet. BPM2 preamp
needs to run on most sensitive scale.