Transcript Slide 1

SPECTRAP meeting
status report
Zoran Andjelkovic
Johannes Gutenberg – Mainz University
GSI Darmstadt
Laser Spectroscopy of Highly Charged
Ions and Exotic Radioactive Nuclei
(Helmholtz Young Investigator Group)
Overview of the HITRAP Facility
UNILAC
Experiments
with particles
at rest
Post
decelerator
Cooler
trap
SIS
400 MeV/u
HITRAP
Stripper
target
SPECTRAP
ESR
• trapping of HCI
• cooling nearly to rest
• laser spectroscopy of HFS
U92+
Pb81+
Bi80,82+
4 MeV/u
Electron cooling
and deceleration
2
Zoran Anđelković
A short progress overview
Vacuum & magnet business:
– high vacuum finally
– energizing the magnet
– LHe problems
Trap stuff:
– (re)redisign
– detector problems
Electronic development:
– design and testing with Stefan Stahl
New-old beamline:
– details from Bettina Sommer
3
Zoran Anđelković
Setup and problem overview
ion beam
bender, beam optics
vacuum leak
He an N vapour
outlets
vacuum leak
300K
electr.
4K
electr.
liquid N
missalignment
fluorescence
SC magnet coils
broken electonics
trap
liquid He
complete break
sealed (after 4
attempts)!
rectified
need new anyhow
replaced
pumps
laser
4
Zoran Anđelković
Vacuum considerations
Three different vacuum seals in use:
• standard copper
~ 5 mm
cross
section
• Helicoflex Delta C-seal
• thick, high-purity aluminium foil
sealing
surface
Found an alternative to
the expensive Helicoflex!
home made PEEK seal
5
Zoran Anđelković
and finally...
we reached high vacuum...
...which improved further
after cooling down
6
Zoran Anđelković
Cooling down and energizing
magnet successfully cooled
and energized to 30 A,
corresponding to ~ 3 T field
7
Zoran Anđelković
LHe problems
1. Although we tried to
improve, LHe hold time
still in the order of a week
2. Need a new level probe
3. Need a low pressure valve
and possibly a gas
collection system
4. Transfer line too short,
the platform needs to be
modified
8
Zoran Anđelković
Trap (re)redesigned
• trap mount slightly altered to meet
the requirements of the cryogenic
electronics – details from Stefan
Stahl
• parts machined, awaiting gold
plating
• (cryogen-friendly) cables obtained
• including a mirror to increase
fluorescence intensity
9
Zoran Anđelković
Magnetic fringe field estimate
2
single current loop
magnetic field on axis / T
1.75
two single current loops in
a Helmholtz arrangement
1.5
1.25
1
0.75
0.5
0.25
0.05
0.075
0.1
0.125
0.15
0.175
0.2
distance from the center / m
10
Zoran Anđelković
How to detect the ions?
plate directly under the trap
• how to get the laser in?
• how to move the plate away?
channeltron under the trap mount
• it does not like the environment
• ion cloud gets blown up
MCP in the bottom of the system
• ion cloud gets blown up
• again, laser in?
11
Zoran Anđelković
Putting the system together
• beamline to be
attached to
HITRAP in the
(near?) future
• "imitating" the
output of
HITRAP and
preparing the
setup
• work done and
presented by
Bettina Somer
12
Zoran Anđelković
Current status
We have:
• platform with infrastructure
• working magnet setup incl. trap
• cryo electronics currently under construction
• assembled beamline
We want:
• better vacuum (always)
• longer LHe life time or some recycling system
Next steps:
• prepare the beamline and the control electronics
• install the trap, electronics and perform tests
• attach to HITRAP or EBIS to get some HCI
13
Zoran Anđelković
Magnetic field 0.2-0.5 m area
0.06
magnetic field on axis / T
single current loop
0.05
two single current loops in
a Helmholtz arrangement
0.04
0.03
0.02
0.01
0.2
0.25
0.3
0.35
0.4
0.45
0.5
distance from the center / m
14
Zoran Anđelković
Beamline(s) after HITRAP
0.4 0.4
H1
H3
B5
DB16
1.2
1.2
1.0
DB13
---------2.0--------
0.4
0.18
0.18
B4
DB11
1.0
1.0
2.0
0.4
0.18
0.18
1.2
B3
DB8
---------2.0--------
0.4
DB14
0.4 0.4
0.4 0.4
1.0
0.18
0.6
DB5
---------2.0-------0.4
0.18
0.4
DB10
0.8
DB3
1.0
2.0
0.18
1.0
0.18
DB1
DB2
-----2.0-----
B2
1.2
0.8
1.2
0.18
0.18
0.4
DB6
H4
0.18
1.2
0.6
1.2
H5
1.2
H2
DB7
EBIS
0.18
1.2
1.2
H6
electrostatic kicker/bender 90° A=20mm, R=250mm
QP doublet, 80/20/80mm, A=40mm
position of beam waist, possible diagnostic position
15
Zoran Anđelković
B1
Beamline & HITRAP platform
MCP
Collimation plates
Vacuum pumps
Electrostatic
bender
Retractable
Faraday Cup
Magnet
system
Source or
HITRAP output
Beam steering
Einzel lens
Deceleration
tube
ion beam line
Trap
assembly
laser light
16
Zoran Anđelković