244pu and 60fe on earth – are there signatures of recent ... ›...

244Pu and 60Fe – signatures of recent supernovae? -- TANDAR 06/2015 -- A. Wallner

244Pu and 60Fe on Earth – are there signatures of recent supernovae?

A. WallnerThe Australian National

University (ANU)

ANU (Canberra, AU): L.K. Fifield, S. Tims, M. Froehlich (Srncik)Hebrew Univ. (Israel) M. PaulNagoya/Tokyo (Japan) N. KinoshitaUniv. of Vienna (AT): J. Feige, R. Golser, W. Kutschera, G. Wallner,

S. WinklerTU Munich (Germany): T. Faestermann, G. Korschinek, K. KnieTU Vienna (AT): M. Bichler, J. SterbaHZDR (Dresden, GER): S. Merchel, S. Pavetich, G. RugelPSI (Villigen, CH): D. Schumann


1. What is dark matter?2. What is dark energy?3. How were the heavy elements from iron to uranium made?4. Do neutrinos have mass?5. Where do ultrahigh-energy particles come from?6. Is a new theory of light and matter needed to explain what happens at very high energies and temperatures?7. Are there new states of matter at ultrahigh temperatures and densities?8. Are protons unstable?9. What is gravity?10. Are there additional dimensions?11. How did the universe begin?

11 Greatest Unanswered Questions in Physics

Discover 2002; US National Research Council's board on physics and astronomy

3. How were the heavy elements from iron to uranium made?


Crab nebulaRemnant of supernova 1054 ADDistance = 6,300 ly, dia = 11 ly

Nuclear Astrophysics in the Laboratory:Search for interstellar matter entering the solar system and EarthSearch for supernova-produced radionuclides on Earth

Hubble

244Pu (80 Myr)60Fe (2.6 Myr)

Atom counting using Accelerator Mass Spectrometry


What is AMS ?

not only 14C-dating !


Radioisotopes are measured with AMS through isotope ratios

Typical range: radioisotope/stable isotope = 10-12 to 10-16

The main challenge in measuring such minute isotope ratiosis the separation of the radioisotope from interfering background of stable isobars / isotopes.

AMS: Mass spectrometric method

Nahuel Huapi lake/Bariloche: 100 km³ = 100*109 m³ = 1*1014 dm³

1 l Quilmes = 1 dm³ -> 1*10-14 !


fundamental physics

applied sciences

68Ge 0.74 years 55Fe 2.7 3H 12.3

44Ti 6063Ni 10032Si 14039Ar 26914C 5 73059Ni 75 00041Ca 104 00081Kr 230 00079Se 280 00036Cl 301 00026Al 720 00010Be 1 388 00060Fe 2 600 00053Mn 3 600 000182Hf 8 900 000129I 17 000 000236U 23 000 000146Sm 68 000 000

239-244Pu, 247Cm …81 000 000 stable isotopes, …..

Some radionuclides measured with AMS


ANU (15 MV) - CanberraVERA (3 MV) - Vienna

Accelerator Mass Spectrometry (AMS) for “all“ isotopes: 10Be, 14C, 26Al, 32Si, 36Cl, 41Ca, 53Mn, 55,60Fe, 59Ni, 99Tc, 129I, 182Hf, 202,210Pb, 210mBi, 228Ra, 229Th, 231,233Pa, 236U, 239-244Pu, 247Cm, SHE


ANU’s AMS facility


ETA CARINAE

Supermassivestar (>100 MSUN )late in life,giant outburst 170 yr ago

Violent bipolarejecta - pre-supernova explosion

8,000 lyHubble

Homunculus Nebula


© R. Diehl Neutrons FusionBB

Solar System Abundances

factor 1000

factor 100 000eutrons!eutrons!


The Chart of Nuclides

Z

N

s & r process

Neutron capture: slow neutron capture (s process) rapid neutron capture (r process)

r process only

3. How were the heavy elements from iron to uranium made?


r-process sites?

rates: ~ 1000:1neutron star mergers

© NASA

core collapse supernovaHubble


Can we find isotopic fingerprints of the ISM (interstellar medium) in terrestrial archives?Radionuclides contain time information as they can serve as radioactive clocks!

Extraterrestrial Radionuclides on Earth


“recent” uptake into terrestrial archives

Extraterrestrial Radionuclides on Earth

oceanexplorer.noaa.govdeep-sea mangenese crusts & sediments

extremely low growth rate (mm/Myr) integrate over tens of Myr efficiently enrich content of ocean water column remote locations – low terrestrial background


in collaboration with

TU Munich: Korschinek, Knie et al.

Hebrew Univ.: M. Paul et al.

244Pu: T1/2 = 81 Myr - AMS at VERA / Vienna


New crust sample for 244Pu

Layer 1 (0-0.5 Myr), bomb test Pu Layer 2a (0.5-5 Myr) 60Fe peak Layer 2b (5-12 Myr) Layer 3 (12-25 Myr) Layer 4: hydro-thermal → blank ?

25 cm2 (110 g): 1ct (TU Munich 2000)

now: →250 cm2 (1.8 kg): ??


SN-isotope 244Pu- new results? Possible „observatories“ of ISM on Earth:

1. Deep-sea sediments :

2. Deep-sea nodules and crusts :

AMS results for 244Pu-search:

TUM: C. Wallner et al. 2000/03 Pacific ferromanganese nodules 1 ct

Rehovot: M. Paul et al. 2003 Pacific sediment 1 ct*

Rehovot / VERA Pacific sediment 1 ct

TUM / VERA Pacific ferromanganese crust 0 & 1+1 ct

*fits to anthropogenic production

new:new:

AW et al. 2015


244Pu – estimated vs measured

-- steady state concentration of 244Pu in the interstellar medium

use Supernova rate in our galaxyuse yield of 244Pu from modelsor use dust mass in galaxyCalculate 244Pu abundance in the ISM

177 (< 575, 2σ limit) 244Pu ats/cm2/Myr

10000: 1 (100000:1) less measured than expected

26 km/s

3x106 (107) ats/cm2/Myr


Dust entering the heliosphere

spacecrafts collect ISD particles passing through the heliosphere



less measured than expected177 (< 575, 2σ limit) 244Pu ats/cm2/Myr

BUT:survival of dust particles?

xx% of 244Pu on average in dust?

fraction of ISD particles entering our SS to 1 AU = Earth orbit? Cassini, Ulysses & Galileo space missions: ISM

mass flux measured


Filtration of interstellar dust entering SS

136: 1 estimated vs measured

42:1 estimated vs meas. upper limit


244Pu particle flux: (20000-160000) 244Pu ats cm-2 Myr-1

ca. 1% of ISD particles make it to Earth orbit


Status:244Pu in terrestrial crust:

crust: dust collection over 25 Myr244Pu: time window - alive a few 100 Myrneutron star mergers?

100:1 estimated vs measured


Actinides – pure r process nuclides

80 MyrAMS – accelerator mass spectrometry

Most sensitive method for long-lived radionuclides= atom counting


Enewetak Atoll, showing location of major tests

Ivy Mike detonation


Pu, U in Environmental Samples Motivation

Pu & U isotopic composition: "fingerprint" of different sources (anthropogenic)

i. atmospheric weapons testing

ii. direct discharge of radioactive wastes

iii. accidental release

iv. minor sources: … low-level radioactive waste disposal, slight leakage from nuclear power plants

erosion studies via Pu-spikes from 60ies (soil and sediment transport & movement)

Nuclear forensics, uranium exploration, biological uptake of actinides, ocean currents, …


AMS studies of neutron-induced reactions on actinides –crucial data for nuclear technology

AMS

neutrons

in collaboration with:

KIT (Karlsruhe): F. Käppeler, I. Dillmann

IRMM / Geel: A. Plompen, A. Krasa

IKI Budapest: T. Belgya, L. Szentmiklosi

TSL Uppsala: A. Prokofiev et al.

VERA (Vienna): P. Steier, S. Winkler, C. Lederer

ANU (Canberra): L.K. Fifield, S. Tims, M. Srncik

ETH Zurich: M. Christl, J. Lachner

ANSTO: M. Hotchkis

Univ. Heidelberg: J. Lippold

IAEA: R. Capote , V. Semkova


Supernova-produced radionuclides on Earth -Live!

GEOLOGICAL ISOTOPE ANOMALIES ASSIGNATURES OF NEARBY SUPERNOVAE

Ellis, J., Fields, B.D., Schramm, D.N., 1996. ApJ 470, 1227G. Korschinek et al., Radiocarbon 38(1): 68-69 (1996)

B.D. Fields, 2004 New Astron. 48, & 2005

Long-lived radionuclides (t1/2 ≈ Myr) WHERE to look for:

• ice core• sediments• deep sea crusts

Which isotopes:

• 26Al, 53Mn, 60Fe, 146Sm, • 182Hf, 244Pu, 247Cm• …e.g. 60Fe from SN: Korschinek, Knie et al.


60Fe: t1/2 = 1.5 / 2.6 / ?3? Myr


Half-life value of 60Fe (1 - 4 Myr?) nucleosynthesis in our galaxy is observed through γ-rays (26Al, 60Fe, …) proof of ongoing nucleosynthesis (on time scale of Myrs) early solar system: decay product 60Ni – surplus in meteorites; heat source = late SN injection of fresh 60Fe into protoplanetary disk (Bizzarro et al. 2007, Wasserburg

et al. 2006) extraterrestrial 60Fe was found in ocean crust material (recent SN origin?)


Half-life value of 60Fe


Half-life measurement

activity measurement

��ሺ��ሻ= ��∙ ��ሺ��ሻ�� ∙ ��

isotope rationo. of atoms

stable isotope

γ-, α-spectrometry, LSC,…

mass spectrometry: ICPMS, TIMS, AMS,..ERDA, …

add stable carrier (well known)


?!AMS & absolute measurements

AMS usually relative to a standard depends often on half-life value


Independent approach: 55Fe is well known and easily measured with AMS

(55Mn no stable neg. ion) measure radionuclides, both as detector countrates use the same detector: about the same concentration!

AMS


ICPMS

AMS

2014

Half-life value of 60Fe:

AMS

AMS

?

new

new


Supernovae


‘Local’ interstellar environment


(182Hf, 244Pu...)

(60Fe...)

( 10Be...)

nearby supernova: < 100 pc, rate ~ 0.3 -10 (Ma)-1

Supernova-produced radionuclides on Earth -Live!

Crab-nebula (SN from 1054 AD)Supernova Remnant at 2000 pc distance

C. Wallner et al. (2000)

WHERE to look for:

• ice core• sediments• deep sea crusts

Which isotopes:

• 26Al, 53Mn, 60Fe, 146Sm, • 182Hf, 244Pu, 247Cm• …

.g. 60Fe from SN


60Fe-signal in a deep-sea crust

Peak at 2-3 Myr!

background level

AMS measurement of 60Fe content of crust at

TU Munich

AMS at Munich

• the only lab yet !


blankstandard


Blank measurements (no 60Fe);commercial Fe

blank level: 0.5x10-16

(4 detector events last 2 years)


4 new sediment cores from the Indian Ocean

Thanks to C. Sjunneskog (FSU) !

10Be26Al53Mn60Fe, …

AMS in progress

SN signal?

Univ. of Vienna, AustriaHZDR, Dresden, Germany

1.7 – 3 Myr

… 0 & 10 Myr

60Fe, 53Mn


! clear signal !! measurements not finished !


Preliminary results for Supernova-search

Deep-sea sediments Deep-sea crusts Deep-sea nodules


• 150 indiv. samples• 4 sediment cores / 2 deep-sea crusts/ 2 nodules• Indian / Pacific / Atlantic Ocean global signal • 60Fe, 26Al, 10Be

Summary:•low 60Fe: blanks (60Fe/60Fe 4x10-17)•no 60Fe: recent (< 7x10-17)•no 60Fe: old samples (>3-7 Myr)•clear signal 1.7 – 3.1 Myr

TU Munich: other sediment samples TU Munich: lunar material

Preliminary results for Supernova-search


Asteroid break-up?

Signal from interplanetary production?

Micrometeorites?


Extra-solar system origin: massive stars = SuperAGB-stars = Supernovae (SN)

Origin of 60Fe?


60Fe entered Solar System & is of interstellar origin!


enny Feige PhD at VERA / VIENNASummary

60Fe at the ANU:•new half-life measurement•clear extraterrestrial influx

244Pu at Univ. of Vienna:•100 times less abundant than expected•rare production – neutron star mergers?


AMS measures long-lived radioisotopes by counting atoms rather than waiting for their infrequent decay.

Why Accelerator Mass Spectrometry?

AMS is 106 times more sensitive than decay counting!

21

2lnt

NdtdN ⋅=

Example for 14C dating ( 14C/ 12C = 1.2x10 -12, t1/2 = 5730 years):

1 mg of modern organic carbon contains: 6x107 14C atoms

Decay counting with LSC or GPC: 0.5 14C atoms per hour

Atom counting with AMS: 5x105 14C atoms per hour

no molecules

Typical range: radioisotope/stable isotope = 10-12 to 10-16

The main challenge in measuring such minute isotope ratiosis the separation of the radioisotope from interfering background of stable isobars.


ANU (Canberra, AU): L.K. Fifield, S. Tims

Univ. of Vienna (AT): J. Feige, R. Golser, W. Kutschera, F. Quinto, P. Steier, G. Wallner, S. Winkler

Atominstitut (Vienna): M. Bichler, J. Sterba

Helmholtz Center (Dresden/Rossendorf, GER): S. Merchel, G. Rugel

PSI (Villigen, CH): D. Schumann, R. Dressler

Collaboration:


ANU’s HIAF - AMS setup

60Fe ↔ 60NiENGE – gas filled magnet60FeO− → 60Fe11+

13.5 – 14.5 MV: ~ 160 MeVTotal transmission: ~ 7-9 %FeO− ~ 0.7 – 5 µAεtot ~ > ‰


Nuclear Astrophysics nuclear astrophysics aims to

understand the origin of the chemical elements and the energy generation in stars

nucleosynthesis chemical evolution in our

galaxy elemental abundance pattern

of the solar system isotopic abundance pattern

of the solar systemDiehl


typical Ni content: 1 – 10 ppm (10-6 – 10-5) typical FeO- current in AMS: 1 uA (6x1012 Fe atoms/sec) 10% transmission: 105 – 106 60Ni atoms/sec towards particle detector

ENGE suppression: ~5000 (93% transmission) 100 – 1000 60Ni in particle detector OK!

60Fe/Fe ~10-15 – 10-16 (60Fe/60Ni ~10-10!!) 1 uA Fe → 2 cts/ hour in detector (10-15) (we have 100 cts so far!) typical blank: 10 ppm (1000 Ni/sec) & measured blank ratio 60Fe/Fe: 0.8x10-16

→ detector suppression: > 107

→ ANU: 14UD + ENGE: > 1011 suppression of 60Ni with >90% transmission in ENGE

ENGE: Ni – Fe separation 60Fe vs 60Ni


Independent approach: 55Fe is well known and easily measured with AMS

(55Mn no stable neg. ion) measure radionuclides, both as detector countrates use the same detector

15MV-HIAF: both, 55Fe & 60Fe ok: gas-filled magnet• bending radius different – both nuclides do not enter

the detector in one measurement setup!

measurements at ANU are all finished; → charge state yield corrections √

AMS


Why high particle energies?

ANU, 14 MV, 11+, 170 MeV energy loss (ENGE foil, N2

ENGE gas + detector foil) 50 MeV lost 120 MeV left for detector

60Fe vs 60Ni

Lab XYZ, 10 MV, 9+, 100 MeVenergy loss (ENGE foil, N2 ENGE gas + detector foil)

57 MeV lost 43 MeV left for detector

low 60Fe count rate → high transmission required


Half-life value of 60Fe (1.5 Myr) nucleosynthesis in our galaxy is observed through γ-rays (26Al, 60Fe, …) proof of ongoing nucleosynthesis (on time scale of Myrs) early solar system: decay product 60Ni – surplus in meteorites; heat source = late SN injection of fresh 60Fe into protoplanetary disk (Bizzarro et al. 2007, Wasserburg

et al. 2006) extraterrestrial 60Fe was found in ocean crust material (recent SN origin?)

Gamma-ray line emission from Galactic 60Fe© ESA: INTEGRAL/SPI team


60Fe performance at the ANU

ENGE – gas filled magnetreference material from PSI – values are related to previous t1/2 measurement

Our goals: search for SN-produced 60Fe measurement of t1/2

nucleosynthesis in massive stars

early solar system ... Position 2

∆E3


60Fe performance at the ANU

ENGE – gas filled magnetFeO− → Fe11+

13.5 – 14 MV: ~ 160 MeVtransmission: ~ 7.5%FeO− ~ 0.7 – 3 µA1µA for 30 min → 10-15 εtot ~ > ‰

2 mg material ~ few 60Fe counts

E2

∆E3

ENGE – gas filled magnetreference material from PSI – values are related to previous t1/2 measurement

Our goals: search for SN-produced 60Fe measurement of t1/2

nucleosynthesis in massive stars early solar system ...

→ half-life value important


Isotope ratios

source 240Pu/239Pu reference Global fallout 0.18 Buessler et al. 1987 Chernobyl fallout 0.39 MacKenzie 2000 Irish Sea sediment 0.05 – 0.25 Kershaw et al. 1995 Thule sediment 0.058 Komura et al. 1984 Mururoa average ~ 0.035 Chiappini et al. 1999 Fangataufa 0.05 Chiappini et al. 1999

and: 238,241,242,244Pu/239Pu, 236U/238U in the environment as sensitive markers-- fingerprints --



Ø a) -- steady state concentration SN rate: (8±4)×10-8 pc-3 Myr-3

SN yield: 244Pu: 10-7 (10-8) Mo mean life time: 117 Myr 3×1041 (1042) ats per pc3 steady state interstellar dust: 26 km/s

244Pu flux: 2×106 (2×107) ats/cm2/Myr

• b) -- steady state concentration dust in our galaxy: 0.11-0.15 Mo pc-3, 1% 238U abundance ESS: 16x10-9 g U/g ISM 244Pu/238U = 0.02 (present value)

2×1042 ats 244Pu pc-3

244Pu flux: 107 ats /cm2/Myr


10000: 1 (100000:1) less measured than expected

26 km/s

3x106 (107) ats/cm2/Myr


136Xe overabundance – 244Pu (81 Myr) origin


Primordial radionuclides on Earth? search for 244Pu (t1/2=81.1 Myr) in nature – produced via r-process in prior to SS

formation search for superheavy elements (SHE) in nature (stable, long-lived)


Survival fraction vs half-life


Half-life measurements problematic: very long half-lives & decay pattern; interference, background,

isotopic & isobaric background

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Half-life value of 146Sm

AMS at ANL


60Fe/56Fe ↔ 60Ni ICPMS AMS

?ICPMS

AMSAMS

?

new

Half-life value of 60Fe


we know fresh radionuclides were injected into the nascent solar system

Early Solar System


Early Solar System

Wasserburg et al. 2006

244pu and 60fe on earth – are there signatures of recent ... ›...

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