Zoran Andjelkovic

Johannes Gutenberg – Mainz UniversityGSI Darmstadt

Laser Spectroscopy of Highly Charged Ions and Exotic Radioactive Nuclei(Helmholtz Young Investigator Group)

SPECTRAP meetingstatus report

Zoran Anđelković2

Overview of the HITRAP FacilityOverview of the HITRAP Facility

UNILAC

SIS

400 MeV/u

ESR

U92+

Pb81+

Bi80,82+

4 MeV/u

Electron coolingand deceleration

Strippertarget

Post decelerator

Cooler trap

Experiments with particles

at rest

HITRAP

SPECTRAP

• trapping of HCI• cooling nearly to rest• laser spectroscopy of HFS

Zoran Anđelković3

A short progress overviewA 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

Zoran Anđelković4

Setup and problem overviewSetup and problem overview

ion beam

pumps

laser

fluores-cence

bender, beam optics

He an N vapour outlets

liquid N

SC magnet coils

liquid Hetrap

4K electr.

300K electr.

vacuum leak

vacuum leak

complete break

missalignment

broken electonics

sealed (after 4 attempts)!

need new anyhow

rectified

replaced

Zoran Anđelković5

Vacuum considerationsVacuum considerations

Three different vacuum seals in use:

• standard copper

• Helicoflex Delta C-seal

• thick, high-purity aluminium foil

crosssection

~ 5 mm

sealing surfac

e

Found an alternative to the expensive

Helicoflex!

home made PEEK seal

Zoran Anđelković6

and finally...and finally...

we reached high vacuum...

...which improved further after cooling down

Zoran Anđelković7

Cooling down and energizingCooling down and energizing

magnet successfully cooled and energized to 30 A, corresponding to ~ 3 T field

Zoran Anđelković8

LHe problemsLHe 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

Zoran Anđelković9

Trap (re)redesignedTrap (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

Zoran Anđelković10

Magnetic fringe field estimateMagnetic fringe field estimate

0.05 0.075 0.1 0.125 0.15 0.175 0.2

0.25

0.5

0.75

1

1.25

1.5

1.75

2

single current loop

two single current loops in a Helmholtz arrangement

distance from the center / m

ma

gn

etic

fie

ld o

n a

xis

/ T

Zoran Anđelković11

How to detect the ions?How to detect the ions?

plate directly under the trap• how to get the laser in?• how to move the plate away?

MCP in the bottom of the system• ion cloud gets blown up• again, laser in?

channeltron under the trap mount• it does not like the environment• ion cloud gets blown up

Zoran Anđelković12

Putting the system togetherPutting 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

Zoran Anđelković13

Current statusCurrent 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

Zoran Anđelković14

Magnetic field 0.2-0.5 m areaMagnetic field 0.2-0.5 m area

0.2 0.25 0.3 0.35 0.4 0.45 0.5

0.01

0.02

0.03

0.04

0.05

0.06

single current loop

two single current loops in a Helmholtz arrangement

ma

gn

etic

fie

ld o

n a

xis

/ T

distance from the center / m

Zoran Anđelković15

Beamline(s) after HITRAPBeamline(s) after HITRAP

H1

H5H2

H6

H4

EBIS

DB1DB2DB3DB5DB8DB11DB13

DB14

DB7

DB6DB10

DB16

electrostatic kicker/bender 90° A=20mm, R=250mmQP doublet, 80/20/80mm, A=40mm

H3

0.81.21.2

0.18

0.8

-----2.0-----1.0

B1B2

B3B4B52.01.0

0.40.4

0.4

0.4

1.2

1.2

1.0 ---------2.0--------

0.40.4

0.4

0.4

0.6

0.6

1.0 ---------2.0--------2.01.0

0.40.4

0.4

0.4

1.2

1.2

1.0 ---------2.0--------1.2

position of beam waist, possible diagnostic position

0.180.180.18

1.2

1.2

0.18

0.18

0.18

0.180.18

0.180.18

1.2

0.18

Zoran Anđelković16

Beamline & HITRAP platformBeamline & HITRAP platform

ion beam line

laser light

Einzel lens

Beam steering

Electrostaticbender

Retractable Faraday

Cup

MCP

Magnet

system

Vacuum pumps

Collimation plates

Trap assembly

Deceleration tube

Source or HITRAP output