Mass Measurements with MRTOF at RIKEN RIBF

Michiharu Wada for the SHE-Mass CollaborationKEK, Wako Nuclear Science Center

NUSTAR Meeting 2018

Mass measurement of short-lived nuclei Summary of measurement @GARIS-II Mc and Nh measurement preparation Plan at the end of ZeroDegree

Why Atomic Mass?p

p p p

n n n

n n nAtom is ≈1% lighter than constituents: Mass Deficits

Mass Deficit = Binding Energy B

Most fundamental nuclear propertyDefines Stability, Decay mode, Structure

Finger Print: Unique value for a nucleus

Derivation of mass：Sn (n-separation energy)

Atomic massΣ constituents

Key values for NucleoSynthesis

G-Wave γ-flash

r-process nova?

optical

Astro Physicist:“We saw the moment of Au Pt synthesis in n-star merger!”

H. Koura

Masses to be measured

Mass Known(δm/m<10-6): 2300Experimentally Synthesized：≈3300

Synthesized but Mass unknown：≈1000

note: many known masses were measured indirectly

Ni

Sn

Ca

Pb

H HHeHe

Li LiBeB B

C CN N

O O OFNeNeNe

NaMgMgMg

AlSi Si Si

PS S S

ClS

ArClArK

Ar

CaKCaCaCa

ScCa

Ti Ti Ti Ti TiVCr Cr Cr

FeMnFe Fe Fe

NiCoNi Ni Ni

CuNi

ZnCuZn Zn Zn

GaGe

GaGeGeGe

SeAs

Ge

SeSeSe

KrBr

Se

KrBrKr Kr Kr

SrRb

Kr

Sr Sr SrYZr Zr Zr

MoNb

Zr

MoMoMo

Ru

MoMo

RuRuRuRuRu

PdRh

Ru

Pd PdPd

CdAg

Pd

CdAg

Pd

CdCdCd

SnIn

Cd

SnSn

Cd

Sn SnSnSnSn

TeSb

Sn

TeSb

Sn

Te Te Te

XeIXe XeXe

Ba

XeXe

BaCs

Xe

Ba BaBa

Ce

BaBa

CeLaCePrNdNd

Sm

NdNd Nd

SmEu

SmEu

Sm

GdGdGd

Dy

GdGd

DyTb

Gd

DyDy Dy

Er

DyDy

ErHoEr Er Er

YbTm

Er

YbYbYbYb YbLu

Yb

Hf Hf Hf Hf Hf

WTaW

ReW

OsOsOsOsIr

Os

PtIrPt Pt Pt

HgAu

Pt

HgHgHgHgHgTl

HgTlPb PbPb

Bi

U

decay, reaction (660)

mass spectrometry

+4

0

-4

log(T1/2)

log (T1/2)

T1/2: 10 ms - 100 ms most abundant

0

50

100

150

200

250

300

350

-8-6-4-202468

c_unk1ppm2016_life.m

cf. AME2016

Mass Measurements of Short-lived NucleiQ-value (decay or

reaction)

In-flight spectrometer

Storage RingPenning Trap

MRTOF (multi-reflection TOF)

Ultra FastLow Precision

FastLow Precision

Isochronous

Electron Cooling

Very SlowHigh Precision

SlowUltra precision

FastHigh Precision

New method

UniversalAmbiguity from levels

TOFI, SPEG ..

GSI ESRIMP CSRe

RIKEN RI-RingISOLDE, JYFL...

RIKEN, Giessen, ISOLDE ..

indirect direct

(1)

(2)

(3)

(4)

(5)

MRTOF Mass SpectrographPo

tent

ial (

V)Open entrance to inject

Close entrance before coming back

go back and forth for ≈200 times

Open exit at pre-defined timing

Detect ions’ ToF

Ion Trap Ion MirrorTOF

detector

(Multi Reflection Time of Flight…)

Ion Mirror

k=k+α

k=k-α

A=205@223lapsA=204@223laps

205Fr+204Fr+ 205Rn+204Rn+

205At+ 100,000 cycles in 3000s

garbages @ different laps

total 7000 events

>90% are no ions

garbage ions can be discriminated by different number of laps

0

1

2

3

4

-40 -20 0 20 40

Cou

nts

/ 2 n

s

ToF - 5652584.8 (ns)

0

1

2

3

4

-40 -20 0 20 40

n = 145 lapsToF(250Md2+) = 5 652 584.8(2.1) ns

ToF − 5 652 584.8 (ns)

250Md++ measurement ≈ 1 event /1000 s

Mass determined with δm/m = 6x10-7

P. Schury et al, PRC 95(2017)011305(R)

≈0.3 ppm precisionA=204

A=205

A=204

A=205

27 μs

27 μs

Y. Ito et al, PRL 120 (2018)0102501

Typical Mass Measurement Results

TOF ( ns )6318500 6319000 6319500 6320000 6320500

Coun

ts /

6.4

ns b

in

1

10

210

310

225 laps65Cu

65Zn

65Ga ( 6.8 kCnts )

65Ge64ZnH

TOF = 6319028.062(77) ns

R = 1.000038095(38)

R = 1.00007063(20)R = 1.00008911(21)

R = 1.00001123(12)

FWHM = 24.9(1) ns

65Cu(stable)

65Ga(RI)

S. Kimura et al, IJMS 430, 134-142 (2018)

δm/m = 3.5x10-8

IrPt

IrPt Pt Pt

HgAu

Pt

HgHgHgHgHgTl

HgTlPb PbPb

Bi

U

PoAtRnFrRaAc

RaAcThPa

UNpPu

EsFmMdNo

130120 140 150

80

90

100

N

Z

AME2016 (incl. indirect)MRTOF (RIKEN-KEK)

Masses Measured in 2016 summer - 2017 spring> 80 masses were measured in total 4 weeks beam time6 first masses in trans-uranium elements (Es, Md isotopes)> 30 first direct mass measurementsknown masses agree in 1σ with Penning Trap data, while a few discrepancy in old indirect measurementsshortest T1/2 = 10 ms, with precision 2x10-7

Y. Ito to PRL 120, 102501 (2018)

P. Schury et al, in preparation

M. Rosenbusch et al, PRC 97, 064306 (2018)

P. Schury et al, PRC95(2017)011305R

Y. Ito et al, in preparation

Ge,BrA≈65

S. Kimura et al, IJMS 430, 134-142 (2018)

Half Life [s]

1 ppm

0.1 ppm

0.01 ppm

10 ppmIn-flight

Penning Traps

Isochronous storage ring

Cooled ions in storage ring blank zone

Typical Mass Measurements before MRTOFShorter half-life, lower precision

No devices for T1/2≈10 ms, δm/m≈0.1 ppm[a] Y. Bai et al., AIP Conf. Proc. 455 (1998)90.

[b] F. Sarazin et al., Phys. Rev. Lett. 84 (2000)5062.[c] R. Knöbel et al., EP. J.A. 52 (2016)138, Chen et al, NPA882(2012)71[d] Yu.A. Litvinov et al., Nucl. Phys. A756(2005)3.[e] http://research.jyu.fi/igisol/JYFLTRAP_masses/[f] https://isoltrap.web.cern.ch/isoltrap/database/isodb.asp[g] H.S. Xu et al IJMS349(2013)162 and others

Half Life [s]

1 ppm

0.1 ppm

0.01 ppm

10 ppmIn-flight

Penning Traps

Isochronous storage ring

[a] Y. Bai et al., AIP Conf. Proc. 455 (1998)90.[b] F. Sarazin et al., Phys. Rev. Lett. 84 (2000)5062.[c] R. Knöbel et al., EP. J.A. 52 (2016)138, Chen et al, NPA882(2012)71[d] Yu.A. Litvinov et al., Nucl. Phys. A756(2005)3.[e] http://research.jyu.fi/igisol/JYFLTRAP_masses/[f] https://isoltrap.web.cern.ch/isoltrap/database/isodb.asp[g] H.S. Xu et al IJMS349(2013)162 and others

MRTOF ISOLDE

65Ga: δm/m=3.5x10-8still agree with Penning trap

219Ra220Ra

219Ra (T1/2=10ms) δm/m=3x10-7

MRTOF plays a role in Mass Measurements

Kimura et al.,IJMS 430 (2018) 134

Y. Ito et al.,to be submitted

Cooled ions in storage ring

MRTOF RIKEN-KEK

GARIS-II

Beam

Target

Cryogenic RF carpet Gas Cell

1st Ion TrapBeam Stopper

2nd Ion Trap

MRTOF Mass Spectrograph2nd Ion Trap

Reaction Products

Ion Mirror (Inject)

Ion Mirror (exit)

Detector

RI ions

Ref Ions

Beam Transport(5m)

SHE-Mass-I @ RIKEN RILAC

Cryogenic gas cell

RF-Carpet(traveling wave)

Recoil Ions

(Central part)

DC cylinder RF Six-pole beam guideLinear RFQ ion trap

Flat RFQ ion trap

α-β Detector (retractable)

Window(0.5μm)

Exit hole（φ0.7mm)

CoCentric Electrodes （pitch:0.32mm)

1st Ion Trap Setup

Bunched Ion Beam

Md, Es…

SHE-Mass-I @ RILAC

Thermalize

Trap

reTrap

1.6 keV bunched beam

ε: 30-40%

ε: ≈20%

εtotal: 1-2%

Thermalize

Trap

Side View Top View

εtotal: >10% anticipated

SHE-Mass-II @E6

4.8m

Bottleneck!

New GARIS-II

Gas Cell

MRTOF

from 2017 Winter

SHE-Mass-II @E6 RIBFLarge free areaGasCell+Trap+MRTOF all in one

Movable behind SHE exp.

Gas Cell

Ion Trap MRTOF

GARIS-II@E6

α

α

α

α

α

spontanous fission

α

α

α

α

α

α102No

104Rf105Db

106Sg107Bh

108Hs109Mt110Ds

111Rg112Cn

113Nh114Fl115Mc

116Lv117Ts118Og

140

278

274

270

266

262

258

254

288

284

280

276

272

268

110

120

103Lr

100 100Fm101Md

99Es150 160 170

Cold Fusion SHN(Pb, Bi + Stable Ion)

(actinide + 48Ca)Hot Fusion SHNDirect Mass （Our Work）

Indirect Mass（Our Work）Direct Mass（GSI）Indirect Mass（GSI）Discovered Nuclides

Proton（Atomic) Number Z

neutron number N

252251250249

254

251

246

278

(Mass Number A)

253 254

257 258

261 262

266

α

α

α

α

α

α

α

Masses to be measured

Place a first bridge to the Island

Japanese Nihonium

Russian Nihonium

Masses of Super Heavy Nuclides1. pin down masses of hot-fusion “island”2. confirm A and Z of hot-fusion SHE

Candidates in first Hot Fusion SHE Mass Measurement

243Am(48Ca, 3n)288Mc→284Nh→280Rg0.5 mg/cm2 2 pμA 8.5 pb 4 /day@GARIS

0.1 0.2 0.3 0.4 0.5

Time (s)

0.2

0.4

0.6

0.8

1.0

Fraction

0.1 0.2 0.3 0.4 0.5

Time (s)

0.2

0.4

0.6

0.8

1.0

Fraction

243Am(48Ca, 4n)287Mc→283Nh→279Rg

288Mc 287Mc

284Nh

280Rg

283Nh279Rg

εtotal= 10%10 events/month !

248Cm(14N, 4n)258Lrother interesting mass measurements

mass anchor for 278Nh

244Pu(48Ca, xn)292-xFl→288-xCn anchor for even hot fusion SHE

BigRIPS200 MeV/u

150 cm He 200 mbar

30 cm He 100 mbar

30 cm He 1 mbar

GARIS5 MeV/u

KISS30 keV Pin Hole

Ion Traps

MRTOF

SAMURAIZero-Degree Mass Ring

SHARAQ

SCRIT(Universal SLOW RI-beam facility)

New Facility

Existing Facility

RIBF Accelerator BuildingRIBF Accelerator Building

RIBF Experiment BuildingRIBF Experiment Building

fRCfRCFixed frequency ring cyclotronFixed frequency ring cyclotron））

SRCSRC（（Superconducting ring cyclotronSuperconducting ring cyclotron））

IRCIRC（（Intermediate ring cyclotronIntermediate ring cyclotron））

BigRIPSBigRIPS(Projectile Fragment Separator)(Projectile Fragment Separator)

SLOWRI

RIPS

prototype SLOWRI

GARIS

KISS BigRIPS +SLOWRI

Parallel Measurements @ 3 facilities of RIKEN RIBF

1. Thermalize in He gas2. Extraction by RF-carpet3. Trap in Ion-Traps4. Mass measurements with

MRTOF

@345, 400 MeV/u238U 50 pnA (3x1011 pps)

48Ca 500 pnA (3x1012 pps)

R

6

0

3.

6

10m

187435

818

SLOWRI

5 MRTOF @ BigRIPS of RIBF

OEDORF Carpet Gas Cell（既存設備） MRTOF-MS

Bunching Trap

PALIS-MTOF

SLOWRI-MTOF

Utilize garbage ions at slits

Cocktail beam of BigRIPS

WNSC-HPSP

With pure RI, T1/2, Mass, Pn

KISS2-MTOF

Multi-nucleon transfer products with

10 MeV/u RI-beam

RI beam

ZeroDegree-MTOF

@ Beam dump, 2nd 3rd reaction

products, with free

ZeroDegree

I.C.

TKE BRIKEN1m shift

Gas Cell (3rd prototype SLOWRI)

mini-MTOF

TRAP MTOF (option)

retractable on rails

(degrader)

ZD-MRTOF @ F11 as 3rd Prototype SLOWRI

F11I.C.

TKE Gas Cell

Trap

@F11 Symbiotic Experiment will be run

* Interaction σ exp. * In-beam γ exp.

e.g.

after their measurements,all garbage goes to F11

mass measurement can use them without extra charge

Case study:In-beam exp for 79Ni region40 pnA U beamA week of run1% our total efficiency

What is expected?

0 5 10 15 20 25

1

10

210

310

410

TOF-all

TOF - 4186.72 us

A=81 (n=190)80 (191)79 (192)

78 (193)

77 (194)

82 (188)83 (187)

84 (186)

85 (185)

7.6 7.8 8 8.2 8.4 8.6 8.8 9 9.2 9.4

1

10

210

310

TOF A=78

TOF - 4186.72 us

78Ni (193)

78Cu (193)

84Ge (186)

Expected TOF Spectrum (simulation)

12.6 12.8 13 13.2 13.4 13.6 13.8 14

1

10

210

310

TOF A=79

79Zn (192) 79Cu (192)

79Ni (192)

17 17.2 17.4 17.6 17.8 18 18.2 18.4 18.6 18.8 19

1

10

210

310

410

TOF A=80

84Ga (186)

80Zn (191)

80Cu (191)

80Ni (191)80Ga (191)

≈25 keV precision

TOF - 4186.72 us TOF - 4186.72 us

Summary MRTOF is compatible to short-lived nuclei Efficient mass spectrograph (multiple nuclides at once) Precise and Accurate (novel referencing method) Applicable to Super Heavy Elements Compatible also to r-process, rp-process nuclides

Collaborators for the SHE-Mass projectM. Wada, P. Schury, Y.Ito, F. Arai, S. Kimura, D. Kaji, H. Haba, K. Morimoto, M. Rosensuch, I.Murray,

J.Y.Moon, T. Niwase, S. Ishizawa, T. Tanaka, A.Takamine, M. Reponen, T. Sonoda, Y. Hirayama, Y.X. Watanabe, H. Miyatake, M. MacCormick, H. Koura, K. Morita, A. Ozawa, H. Wollnik

Wako_Nuclear Science Center, IPNS, KEK Nishina Center for Accelerator-based Science, RIKEN Institute of Physics, Tsukuba University Advanced Science Center, Japan Atomic Energy Agency Department of Physics, Kyushu University Institute of Basic Science, Korea University Paris-Scaley, France New Mexico State University, USA