24 January 2001J. Lettry1 ISOLDE - 2000 Introduction –PSB-beam, Targets –Ion-sources Facility...

24 January 2001 J. Lettry 1

ISOLDE - 2000ISOLDE - 2000• Introduction– PSB-beam, Targets

– Ion-sources

• Facility performance – Front-ends and robots

– Target production

– Safety

– Physics shifts

• Target developments– Yields (p-Energy)

– n-converter

– Alkali suppression

– Future developments


Introduction

• PSB-beam

• Targets

• Ion-sources

• Separators

H-scan of the PSB beamon a UC2 target

0

500

1000

1500

-20 -10 0 10 20

Dist. from target center [mm]

23N

e co

untr

ate

(20m

s co

llect

ion)

0%

20%

40%

60%

80%

100%

p+ o

n ta

rget

1GeV 13may

Simul H

Beam shape (2) of the PSB proton beamat the ISOLDE target (G.C. 4-2000)

Contour plot for 90% of a proton pulse of 3E+13 ppp

Beam waist Standard beam

Typical size of ISOLDE targets

10 mm1.4 GeV

1.0 GeV

Uranium carbide (14mm)

2 Ta-foil (10x10mm)

Metal foil rolls ( 19mm) RIST

Protons

+/- 8V500A

+/- 9V1000A

*

RILIS laser beams

Nb cavity

Tantalum oven

Transfer line

Ionisation

Effusion

DiffusionDiffusion

Nuclear reaction

UC2 pills

UC2 target

Graphite sleeve

0.1

1

10

100

1000

10000

100000

1 10 100 1000 10000 100000

T delay + 1/2 collection [ms]

Co

un

t ra

te [

Hz]

Data

Bg & Coll. Corr.

Release of 25Na

UC-118 2100C


High energy protons on 238-uranium - the production cross sections are summed for all isotopes of an element

- the total cross section are given for 0.6, 1 and 1.4 GeV protons.

1E-3

1E-2

1E-1

1E+0

1E+1

1E+2

1E+3

0 10 20 30 40 50 60 70 80 90

Element (Z)

Tot

al c

ross

sec

tion

[m

barn

]

1.4GeV 2.59 barn

1GeV 2.48 barn

600MeV 2.25 barn

Fission

Spallation

Fragmentation


0

20

40

0 1000 2000 3000

ppp [1E+10]

p-d

ens

ity [

1E

+1

0/m

m2

]

1 GeV Standard beam

1.4GeV Standard beam

1 GeV Waist of beam

1.4GeV Waist of beam

Fit.

Temperature increase in a ta diskp-pulse : 3E+13 protons / 2.4 us

0

100

200

300

400

500

600

700

0.00000001 0.000001 0.0001 0.01 1

Time [s]

Te

mp

era

ture

[d

eg

.C]

Beam focus 3 [mm]

Beam focus 6 [mm]

p+ beam density on ISOLDE targets: 90% ppp / 4*h*v


Elements Elements & Ion Sources& Ion Sources

ECR

Negative

PLASMA

LIS

Surface

0

5

10

15

20

25

0 20 40 60 80 100Z

Ion

isa

tio

n p

ote

nti

al

[e

V]

Noble gases

F-group

Actinides

Lantanides

B-group

Alk. earth

Alkali


Efficiencies of ISOLDE ion-sources

1 + ionization

0.1%

1.0%

10.0%

100.0%

0 4 8 12 16 20 24

Ionisation potential [4-25 eV]

Ioni

satio

n ef

ficie

ncy

RILIS

ECR

FEBIAD

W-surface

Electron Affinity [0-4 eV]

LaB6-surf.

ISOLDEISOLDE RILISRILIS

0

0.5

0 10 20 30

time [s]

Ion

beam

cur

rent

[a.

u.] Nb-cavity

Ag+

Sapphirecavity

Ag+

High temp.

Ta-cavity

LIS-ion bunch

time structure


Facility performance

5 years average: 1 Shift ~ 2.5E17 protons

8h PSB at 6x3E13 p/scy ~ 3.6E17 protons =70%

Target assembly

0

1

2

3

1990 1992 1994 1996 1998 2000 2002

0

10

20

30

Manpower Targets Built

HRS operational,

Robot singularity caused

by grip and forearm alignment

0E+00

4E+19

8E+19

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

PS

-un

its [

# p

roto

ns]

0

100

200

300

400

ISO

LD

E u

nits

[#

sh

ifts]

/ [1

0h

]

Protons

HT on

Physics


Safety issues

• Light internal contamination during observation on the HRS front end– Long term follow up described in the ISOLDE consolidation project (M.L.)

– E. Kugler is the new ISOLDE GLIMOS.

• UC2-Pills fire– Follow up completed,

– Pills production resumes next week.

• Break of a Ta-carburisation oven – Physics run delayed by 2 days.

• Storage of Chemicals– ~10 man-weeks required to reorganize the storage.

– PS-PP supervisors for EP-PS shared chemical labs.

• Hg Laboratory (-fact)– Hasop study of the Hg pump for high magnetic field tests done, assembly started.

Electrostatic quadrupole tripletVacuum vessel

Target

ISOLDEISOLDE frontfront endend

Ion source

-60kV

Grounded x-y-z movable

extraction electrode

Ion beam

Turbo molecular pumps

(21000 l/min)


Target developments 2000

• Alkali suppression

• n-converter

• Yields (p-Energy)

• LIS for “low” IP elements, Ga

• Future developments


1

10

100

1000

10000

1 100 10000time [ms]

Co

un

trate

[-

]

0

1

2

3

4

5

6

7

8

9ra

tio

[-

]

1

2

3

4

5

6

3.5 4 4.5 5 5.5 6

IP [eV]

ratio

[D+

/ D-]

(E0+(1-Eo)*D_eff.) / (E0*D_eff.)E0= 79% Weff.= 5.4 eV

Standard

Reversed

E-field

*

+

-

+/- 8V500A

+/- 9V1000A

-

+ +/-300V

While Low IP elements are surface ionized

in the Ta-target oven and feel the

DC heating current E-field,

high IP elements remains unaffected

Ratio of the release curves under Standard and reversed polarity of the target container

E0 ~ ratio of the front and rear

extraction holes surfaces

Deff = /(1+)

with =i/o exp{-(W-IP)/kT}

Reduction of low IP isobars Reduction of low IP isobars

produced in the high temperature produced in the high temperature

metallic cavity of the RILISmetallic cavity of the RILIS

Release curves

Alkalis Rare earth

In neutron induced fission, the spallation and fragmentation processes are absent. Therefore, isobaric contamination

is reduced by ~ 2 orders of magnitude

Towards pulsed high power U &Th targets Towards pulsed high power U &Th targets

delivering very n-rich fission productsdelivering very n-rich fission products High energy protons (~1GeV)

impacting on Ta- & W-rods (converters) generate an intense neutron flux.

The yields of very n-rich isotopes obtained via neutron induced fission of Th or U

are close to those of high energy protons.Further developments:

Geometrical optimum and n-reflectors

ISOLDE target and ion-source unit

W-converter

Ion-source

PSB protons

p+ beam-scan

0

10000

20000

30000

0 5000 10000 15000

time [ms]

90K

r Io

n cu

rren

t [a

.u.]

0

1 000

2 000

3 000

4 0001GeV protons

n-converter

The thermal shock of the proton’s dE/dx

is on the “cold” converter.

The ion-release time structure is kept

UC2 target

0

2

4

6

8

10

135 140 145 150

Xe mass [amu]

1GeV

1.4GeV

0

2

4

6

8

10

85 90 95 100

Kr mass [amu]

Y (

p)

/ Y

(n

)

UC2 + W-converter

HT-oven electrical connections


ISOLDE UC-target with Ta n-converter

Beam waiston converter

Standard beamon target

10 mmUC2-Target(14 x 190 mm)

Ta-converter( 10 x 200 mm)

Cs-yields UC2-183

1E+0

1E+1

1E+2

1E+3

1E+4

1E+5

1E+6

1E+7

1E+8

1E+9

1E+10

132 134 136 138 140 142 144 146 148 150

Cs mass

Yie

ld (

1/

C)

0

20

40

60

80

100

rati

o [

-]

p+ on UC-targetp+ on Ta-converterRatio

142Cs (1GeV p+)

Yield unit : [ions / micro Coulomb of protons]

Historical unit from SC time [ions / s A protons]

1C protons = 6.25x1012 protons

highest Yields of the order of few ions / 1000 protons

Spallation Fission


RILIS application on “low” ionization potential elements

1E+0

1E+1

1E+2

1E+3

1E+4

1E+5

1E+6

1E+7

1E+8

72 74 76 78 80 82 84Mass

Ga

Yie

ld (

1/

C)

Direct on target

Converter

Converter + RILIS

On line Ga tests, despite old CVL tubes,

IS efficiency increased by one order of magnitude.

The deep spallation product suppression is visible.

Elements with IP close to 6 eV

were surface ionized,

a substantial ionization efficiency

increase of ~ 30 was obtained off line.


2001 developments• 1+ ECR for ISOLDE• 2 Nb target• Alkali suppression for Spectroscopy within the

LIS cavity• n-converter study• New LIS elements:

– Germanium – Antimony

*

++/- 8V500A

-

300V-+/- 9V1000A

+-

Conclusion

A hell of a job…

We did it…Thank to your support

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24 January 2001J. Lettry1 ISOLDE - 2000 Introduction –PSB-beam, Targets –Ion-sources Facility...

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