Mass measurement with the Rare-RI Ring at
RIBF/Riken elucidates r-process abundancesof heavy elements at A=122,123
Sarah Naimi

24 Mar. 2022, TCHoU Workshop

24 Mar. 2022, TCHoU Workshop

Gravitational Waves discovery
Neutron star mergers!

The light was also observed
This is very exciting for our field!!!

LIGO observatory in USA

24 Mar. 2022, TCHoU Workshop

The nuclear physics

Neutron is converted to proton via beta decay. Number of protons defines the element.

24 Mar. 2022, TCHoU Workshop『How were heavy elements made ?』rapid neutron capture: r-process
612=UNenc2a=8ndNuablaroS50
N=Feβsayr escutdecaprontN eu

24 Mar. 2022, TCHoU Workshop

The nuclear physics????

Neutron is converted to proton via beta decay. Number of protons defines the element.

24 Mar. 2022, TCHoU Workshop

RIKEN Campus & RIBF

24 Mar. 2022, TCHoU Workshop

RI Beam Factory at RIKEN
3 injectors + cascade of 4 cyclotrons⇒ several to 345 MeV/nucleon
A variety of primary beams
World highest-intensity RI beamsECRRILAC
CSM

RILAC2RIPS

AVF

SAMURAI
ZeroDegree

Rare RI Ring

RRC
SRCfRCSCRITGARIS &GARIS2SLOWRI
SHARAQKISSBigRIPSIRC

24 Mar. 2022, TCHoU Workshop

Production of RI beam at RIBF

24 Mar. 2022, TCHoU Workshop

X

The Massof the Atom
Nuclear binding
energyM(4He) = 2 ⋅ mp + 2 ⋅ mn + 2 ⋅ me- Binding Energy

42H
2HHe

24 Mar. 2022, TCHoU Workshop

Specifications
Circumference
Betatron tune
Momentum acceptanceTransverse acceptance
RI beam energy
Revolution frequency

60.35m1.21 / 0.84
±0.5%
20π / 10π mm mrad
200 MeV/u
2.82MHz2012 Construction started
2013 Completed
2014 Test of devices
2015 1st & 2nd commissioning
2016 3rd commissioning2017 4th commissioning
2018 1st physics run
2020 Kicker upgrade24 Mar. 2022, TCHoU Workshop

RI Beam Factory at RIKEN
3 injectors + cascade of 4 cyclotrons⇒ several to 345 MeV/nucleon
A variety of primary beams
World highest-intensity RI beams

ECR

RILAC
CSM

RILAC2RIPS

AVF

SAMURAI
ZeroDegree

Rare RI Ring

RRC
SRC

fRC

SCRIT

GARIS &GARIS2SLOWRI
SHARAQKISSBigRIPSIRC

24 Mar. 2022, TCHoU WorkshopZ. Ge (IMP)Hongfu Li
PhD Riken/IMP

Prof. Ozawa
Tsukuba Univ.

24 Mar. 2022, TCHoU Workshop
X

South of 132Sn(N=82)

Production yields measured (1460)

New isotopes (2007–2018)
238U in-flight fission (119)Near 78Ni(Z=28, N=50)

124Xe P.F. (10)78Kr P.F. (3)70Zn P.F. (8)24 Mar. 2022, TCHoU Workshop

24 Mar. 2022, TCHoU Workshop

Shell quenching at N=82 & Z<50?

Mass measurement across N=82 132Cd @ISOLDE/CERN
Pearson et al. Phys. Lett. B 387, 455 (1996).

Manea et al., Phys. Rev. Lett. 124, 092502 (2020).

24 Mar. 2022, TCHoU Workshop

Deformation below Z=50?

24 Mar. 2022, TCHoU Workshop

Deformation below Z=50?
<−2−4−4−6−6−8−8− 10− 10− 12− 12KTUY

HFB14
1

110− 110− 1−2−21010− 14100

110

KTUY

HFB14−2120

130140150100110

120

130140150

60

6570758085

90

− 141

10− 110− 210− 2−2−2−4−4−6−6−8−8− 10− 10− 12− 12− 14110

707580

8590

ETSIQ

FRDM

10− 110065

ETSQI (enhanced quenching)

FRDM

16012013014015010011012013014015060657075808590− 1460657075808590

24 Mar. 2022, TCHoU Workshop

RI with short half-lives and low production yield

Unknown masses

24 Mar. 2022, TCHoU Workshop

Specifications
Circumference
Betatron tune
Momentum acceptanceTransverse acceptance
RI beam energy
Revolution frequency

60.35m1.21 / 0.84
±0.5%
20π / 10π mm mrad
200 MeV/u
2.82MHz2012 Construction started
2013 Completed
2014 Test of devices
2015 1st & 2nd commissioning
2016 3rd commissioning2017 4th commissioning
2018 1st physics run
2020 Kicker upgrade24 Mar. 2022, TCHoU Workshop

Union of storage ring & cyclotron

24 Mar. 2022, TCHoU Workshop

Critical Mismatch!!
DC beam vs. pulsed beam
How to solve?
The Rare-RI Ring (R3)DCAC

24 Mar. 2022, TCHoU Workshop

Phys. Scr. T166 (2015) 014039

Figure 1. Schematic drawing of the beam structures of thesynchrotron- and cyclotron-based storage ring.

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Enhancement of particle
selection for R3

Y. Abe et al., RIKEN Acc. Prog. Rep. 52 (2019)24 Mar. 2022, TCHoU Workshop

Position detector
is too thick, energy loss introduces
uncertainty in beta measurement!
Massmeasurement
principle

F3F5 position detector (PPAC)(dispersive plane)
β1 meas.

T0, T1 meas.

S0
m0 is known mass
m1 is unknown mass

24 Mar. 2022, TCHoU Workshop

Beta determination

127Sn and 124Ag were used to determine the two parameters

Search ranges: Length = [84.8m, 84.9m], TOFoffset = [325.35ns, 325.55ns]
Length = 84.8592 m
TOFoffset = 325.47 ns
Get B𝜌0 & 𝛾t
C0 = 60.3507 m

24 Mar. 2022, TCHoU Workshop

New R3 mass measurement result

H.F. Li et al. PRL 2022 accepted

No evidence of large deformation below Z=50!!

24 Mar. 2022, TCHoU Workshop

Impact in r-process abundances

Portable Routines for Integrated nucleoSynthesis Modeling (PRISM)
reaction network, neutron star merger condition; entropy 40kB/baryon,timescale 20ms, electron fraction Ye=0.15~0.35.
Mumpower et al. PRC92(2015), Zhu et al., Astro. J. 863 (2018)
Mass model FRDM (baseline),
Our new mass measurement of 123Pd (redline) with its uncertainty

24 Mar. 2022, TCHoU Workshop

Impact of 123Pd mass
Neutron capture cross section:
122Pd ↓ 2.6
123Pd ↑ 2.2
Probability 𝛽-delayed neutron emission
123Rh ↑
Mass difference FRDM ~500keV

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24 Mar. 2022, TCHoU Workshop

Thank you!
ありがとうございます！

24 Mar. 2022, TCHoU Workshop

24 Mar. 2022, TCHoU Workshop

Challenge #2
Minimizing energy loss on beamline

24 Mar. 2022, TCHoU Workshop

Position detector is too thick, energy loss introduces uncertainty in beta measurement!

F3

F5 position detector (PPAC)(dispersive plane)
β1 meas.

T0, T1 meas.

S0S. Suzuki, NIMA 965 (2020)
𝞂 = 38ps, eff = 95%, dE/E<10-5

24 Mar. 2022, TCHoU Workshop

Large area position-sensitive DL-E-MCP
Thin foil à low energy loss

G. Hudson-Chang
Master (Surrey Uni.)

Z. Ge, PhD(IMP/Riken)

R. Crane
Master (Surrey Uni)

24 Mar. 2022, TCHoU Workshop

Comparison with PPAC resolution
PPAC

DL-E-MCP

24 Mar. 2022, TCHoU Workshop

G. Hudson-Chang
Master (Riken/Surrey)

Compact

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Challenge #3
Matching emittance at ring injection

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Lower acceptance!

Experiment

Before R3

A*er R3

24 Mar. 2022, TCHoU Workshop

After

Redesign the injection optics for Rare-RI Ring

Efficiency: x14 times
Total R3 eff. 2%
F3S0

ILC1

ILC2

RMD-4

ELC

100

Transmission Efficiency [%]BeforeGoal (10%)
10Exp. New Optics
1Exp. Standard Optics
Simulation

0.1

Injection
into ring

14 times
increase!!

24 Mar. 2022, TCHoU Workshop

Large area position-sensitive DL-E-MCP
New kicker magnets configurationa bc dKicker magnets

DL-E-MCP could be placed inside the kicker
magnet to monitor emittance24 Mar. 2022, TCHoU Workshop

Challenge #4
Determination of revolution time

24 Mar. 2022, TCHoU Workshop

Position detector is too thick, energy loss introduces uncertainty in beta measurement!

F3

F5 position detector (PPAC)(dispersive plane)
β1 meas.

T0, T1 meas.

S0

S. Suzuki, NIMA 965 (2020)
𝞂 = 38ps, eff = 95%, dE/E<10-5

24 Mar. 2022, TCHoU Workshop

Kicker24 Mar. 2022, TCHoU Workshop

Rough determination of revolution time à deduce turn number10000

Timing detector

Count [1/bin]R31000
100101050 mm

100 mm- Efficiency: 90 %- Time resolution: 70ps

D. Nagae et al., NIMA 2020

5000

10000

15000

Time [ns]

20000

25000

24 Mar. 2022, TCHoU Workshop

 (almost) Perfect Isochronicity!
November 2017

78Ge beam-60

fcenter = 173.378 MHz"/Users/suzaki/Desktop/spectrogram/ev52/text/55ms/2culmn/sp3.txt" u 1:2-65

6106  Highest sensitivity Schottky pickup detector→ detection of Z=32 (lightest isotope ever)Power [dBm]-70-75-80-8578Ge signal-90173.37173.375

173.38Frequency [MHz]173.385

24 Mar. 2022, TCHoU Workshop

Challenge #5
Ejection from the ring

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Kicker limitation at ejection

24 Mar. 2022, TCHoU Workshop

Upgrade of the kicker magnets
Previous config.

abcabcb, c for injectiona, d for ejectiond24 Mar. 2022, TCHoU Workshop

R3 in-ring detectors
Septa
for extraction

Resonant
Schottky pick-up

DL-E-MCP
Position-sensitive

Position-sensitive
Schottky pick-up ?

Plastic counters

Septa
for injection
1 dipole
Timing detector(C-foil + MCP)
Nagae et al.
NIMA 2020

10 quadrupolesSelected RI(from BigRIPS)

Delta-ray monitor
Timing detector
Omika et al., NIMB 2020

24 Mar. 2022, TCHoU Workshop

Monitoring F5 position is necessary for verifying the isochonicity** Revolution time is independent of momentum24 Mar. 2022, TCHoU Workshop

Self-trigger injection method
CyclotronNE
Storage ringW!
!

In-flight separator
Fast-kicker system

Trigger signal(Kickermagnets)

R3SRC
Injecting RI
F0F3BigRIPS(Septum)

Proposed by I. Meshkov et al., NIMA523 (2004)

24 Mar. 2022, TCHoU Workshop

Storage of single-ion (@MS01)
Schottky_Spectrum_../../Desktop/all_data_MT/mea1_21_afternoon/20150621-171529-0081011980.iqt
Repetition
time of injection : 0.5s

R377801477707760

12Time →Time [bin]7750

Tuners107740

87730

7720

67710

47700

7690

Ceramic
tube
Pick-up coupler

7680

21 frame : 32ms
×106173.81173.82173.83173.84173.85173.83173.84 173.85
173.81 173.82
Frequency[MHz]

Resonant Schottky pick-up

Resonance frequency :Tuning range :±1.5MHz
Shunt Impedance Rsh :Quality factor Q0 :Ceramic tube size :thickness

Resonance frequency [MHz]173MHz (TM010)
161kΩ
1880
290mmΦ, 15mm

- Succeeded in detecting the single 78Kr36+ ion- Frequency resolution: ~1.3x10-6 (FWHM)

24 Mar. 2022, TCHoU Workshop
XIn November 2018: 74,76Ni isotopes were measured
77Ni is planned to be measured in 2021

ryrynaimli

Prenaimli

Pre

76Zn

78Zn

76Ni

74Ni

Production yields measured (1460)

New isotopes (2007–2018)
238U in-flight fission (119)Near 78Ni(Z=28, N=50)

124Xe P.F. (10)78Kr P.F. (3)70Zn P.F. (8)24 Mar. 2022, TCHoU WorkshopX

expimentally known masses
theore2cal masses

HFB-19Astrophys. J. 816, 44 (2016)

R.N. Wolf et al.,PRL110, 041101 (2013) Production yields measured (1460)
New isotopes (2007–2018)
238U in-flight fission (119)Near 78Ni(Z=28, N=50)

124Xe P.F. (10)78Kr P.F. (3)70Zn P.F. (8)