TOF Mass Measurements: Status and Future

(or When the Masses of the R-Process Nuclides will be Measured?)

Milan MATOŠ

JINA Frontiers August 20, 2007

Known Masses (AME 2003)

r-process

ETSFI-Q dripline

Mass Measurement TechniquesPenning traps Time-of-Flight

very precise ~ 1 keV less precise ~100 keV

half life > 10 ms half life > 1s

rate > 100 part/s after the nuclide production

rate > 0.01 part/s after the nuclide production

complex simple

expected to be first to measure r-process masses

Principle of Time-of-Flight Mass Measurements

vq

mB t

Lv

constB

constL

tconstq

m

constB usually B acceptance ± several percent

solutions

B measurement

constL

B

isochronicity

t constant for fixed m/qeven if v1 < v2

xB

dispersive mode

Existing Time-of-Flight Mass

Measurement Facilities

B measurement isochronicity

multi-turnlinear

flight path

B distribution

TOFI at Los Alamos

SPEG at GANIL

TOF start

length ~82m

position (B )

target

TOF stop

position (B )dE-E (identification)

productiontarget

productiontarget

productiontarget

productiontarget

productiontarget

productiontarget

productiontarget

productiontarget

productiontarget

productiontarget

10m

Isochronous Mass Spectrometryin ESR (at GSI)

In jectionIn jectionIn jection

tim e [ s]

U [V ]

0 1 2

0

-0.5

tim e [ s]

U [V ]

0 1 2

0

-0.5

IMS at GSI

TOF-Bat the NSCL

10m

K500

K1200 A1900

transfer hall

S800TOF startTOF stop

B meas.

path length ~ 58m

fast PMTs:Timing Resolution ~ 30ps

MCP: Position Resolution

< 0.5mm

see next talkby A. Estrade

Comparisons

TOFI

at LANL

SPEG

at GANIL

SMS

at GSI

TOF-B

at NSCL

B

distributionisochron. Br meas. isochron. Br meas.

flight path N/A 82m 100 x 108m 58m

relative

resolutionN/A 1x10-4 2x10-5 1x10-4

relative

uncertainty2x10-6 1-2x10-6 1-2x10-6 1-2x10-6

typical

energyN/A 40 MeV/u 350MeV/u 100MeV/u

Isochronicity vs. B measurement

Comparisons

easy to set updifficult to set up

no B measurement needed (no detector) position sensitive required

low large energy losses in detectorslarge energy losses in detectors

low energy vs. high energylow charge contaminationlarge charge contamination

unlimited m/q range for one settinglimited m/q range for one setting

linear vs. multi-turn

shorter flight timelonger flight time

better resolutionworse resolution

limitation on total statistics < 10ppstotal statistics < 1000pps

isomeric contamination:resolved for E > 500keV

isomeric contamination:fully covered by detectors

transmission ~ 0.1%transmission ~ 10%

TOF (yellow) vs. Penning traps (blue)

RIKEN – BigRIPS

RIKEN – BigRIPS+ ZDSE ~ 350MeV/A

TOF start/stop (88 m)

B measurement

FAIR – isochronous CR E ~ 1.5GeV/A

ILIMA project

ISF at MSU

E ~ 250MeV/A

ISF at MSU

E ~ 250MeV/A

Future Facilities Rates

FAIR: 2012 first experiments 2015 completion

ISF: 2016 if approved

Big RIPS: 2007 first experiments

timelines

rate needed ~ 0.01pps

rate needed ~ 0.01ppsrate needed ~ 0.1pps

Conclusions

in 5 years – first large r-process areas by RIKEN Z < 40 & Z~50in 10 years – Z < 40 & Z~50 fully covered by MSU or GSIIn 15 years – Penning trap measurements in the r-process area

penetration into more exotic r-process areas In 20 years – ????

• competition has already started• who will be the winner? depends on decisions • many surprises are expected• theoreticians (nuclear models, r-process) should be prepared

JINA should be involved