Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New...

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Muon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation with ortho/para D 2 Prospect with intense muon beam in collaboration with K. Nagamine 1,2* , T. Matsuzaki 1 , S. Nakamura 1** , N. Kawamura 2 , M. Iwasaki 1 , Y. Matsuda 1 , A. Toyoda 3*** , H. Imao 3 , M. Kato 4 , H. Sugai 4 , A. Uritani 5 , H. Harano 5 , G.H. Eaton 6 1 RIKEN, 2 KEK, 3 U. Tokyo, 4 JAERI, 5 AIST, 6 RAL present address * UC Riverside, **KEK, **U. Tohoku NuFact-J 05研究会, 東工大 2005.06.09

Transcript of Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New...

Page 1: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Muon Catalyzed Fusion (μCF) - New progress and future plan

K. Ishida (RIKEN)

IntroductionNew progress

Muonic molecule formation with ortho/para D2Prospect with intense muon beam

in collaboration withK. Nagamine1,2*, T. Matsuzaki1, S. Nakamura1**, N. Kawamura2,M. Iwasaki1, Y. Matsuda1, A. Toyoda3***, H. Imao3, M. Kato4, H. Sugai4, A. Uritani5, H. Harano5, G.H. Eaton6

1RIKEN, 2KEK, 3U. Tokyo, 4JAERI, 5AIST, 6RALpresent address * UC Riverside, **KEK, **U. Tohoku

NuFact-J 05研究会, 東工大 2005.06.09

Page 2: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

What is muon catalyzed fusion (μCF)?After injection of muons into D/T mixture (or other hydrogen isotopes)

Formation of muonic atoms and muonic moleculesnucleus-nucleus separation ~1/200 of normal atom

In small dtµ molecule, Coulomb barrier shrinks and d-t fusionMuon released after d-t fusion

- muon works as catalyst - tµ

µdtµ

µ

nuclearfusion

αμ

d14MeVneutron

3Heµ

Sticking

Page 3: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

µCF (Motivation)Exotic atoms and molecules

atomic physics in small scalerich in few body physics problems

dt fusion and alpha-stickingdtµ energy levels and formationatomic collisions, muon transfer

Prospect for applications(fusion energy, fusion neutron source)

muon production cost (~5 GeV)vs

fusion output (17.6 MeV x 120)very close to breakeven

µdtµ

µ

dtµformation

nuclearfusion

effective stickingωs=(1-R)ωs0

αμ 17.6MeV x Ynenergy output

injectedmuon

d

Kα/KβX-ray

14MeVneutron

3Heµtransfer toHe

Page 4: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Maximizing µCF efficiencyObservables

(1) Cycling rate λc ( ) (vs λ0: muon life)dtµ formation tµ + D2 [(dtµ)dee]

(2) Muon loss per cycle W ( )

muon sticking to α-particle is the main losstransfer to 3He is also important

Number of fusion per muon

Yn = φλc/λn = 1 / [(λ0/φλc)+W] ( )tµ

µdtµ

µ

dtµformation

nuclearfusion

effective stickingωs=(1-R)ωs0

αμ 17.6MeV x Ynenergy output

injectedmuon

d

Kα/KβX-ray

14MeVneutron

3Heµtransfer toHe

Page 5: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Key process of µCF - dtµ formation

Auger formation : 106 /s (as slow as muon decay rate 0.45 x 106/s)tμ + D2 (dtμ) + D + e-

Resonant molecular formation : 106-109 /stμ + D2 ((dtμ) dee)

(dtµ binding energy ~ excitation of complex molecule)

(tµ energy to match the small energy difference)

Thus,large temperature dependencedependence on initial states(such as tμ spin state, D2 states)

We could change (enhance) μCF by controlling initial D2 states.

ΔE ν = ε11dtμ + ε0

tμ + (D2)νiKi → [(dtμ)11dee]*vfKf

d d dtμd

e-

e-

e-

e-

→+μ

μ

dtμU

R

D2

ΔEνε11dtμ

ε0tμ

ν = 0

ν = 1

ν = 2

J,ν = (0,0)

J,v=(1,1)ν = 0

[(dtμ)dee]

~0.3eV

Page 6: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Present understanding of dtµ formationdtµ molecule formation

large formation rate (~109/s) by resonant formation mechanismis established (temperature dependence, etc)still many surprises

non-trivial density dependence even after normalizationthree-body effect : tµ + D2 + D2’ ((dtµ)dee) + D2’’

low temperature & solid state effectφ dependence applies even to solid

density φ

Page 7: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

How about ddμ ?Same resonant formation process applies for ddμ formation in pure D2

Slower compared to dt-μCF, and with lower energy output per fusionStill, study should be done in parallel with study of dtμ

No need of tritiumSimpler cycling process (pure D2)

dμ + D2 [(ddμ)dee] In analogy to dtμ case,

temperature dependencedμ Hyperfine effect (F=1/2,3/2)D2 molecule effect

Page 8: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

What has been known about ddμ formationResonant ddμ formation is nearly established in gas

fitting by theoretical curve givesprecision determination of shallow state binding energy in ddμ (-1.97 eV) which is comparable to the valueby precise three-body calculation

However, in liquid and solid, large deviation from theoretical curve

Ki=0

2

Ki=3 4

10 200

~5K

~20K~50K

F=3/2

F=1/2

共鳴位置とMaxwell分布

共鳴エネルギー[meV]

(ortho)

(ortho)(para)

Page 9: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Ortho- and para-D2 in μCFAll the measurements so far were with normal D2 (ortho:para = 2:1)Thus, the resonance condition for ortho- and para- are mixed.

Ortho-D2 (dd nuclear spin coupled with 0,2, ψ spin ψJ,v symmetry under ddexchangeonly J=even allowed)Para-D2 (simillary, for coupling with 1, J=odd allowed)

Resonance condition for each state should be separately measured.

Page 10: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Experimental setup @TRIUMFortho-D2 and normal-D2 preparationortho-para ratio analysis with Raman spectroscopyTarget cell (30cc liquid/solid, or 200cc pressurized gas)muon beam counters B1+B2me-decay electron counters E1-E8 (>50% solid angle)neutron detectors(NE213) N1-N4

0 10cm

target

Page 11: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

muonbeam

gas preparation D2 target and detectors

Page 12: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Typical fusion neutron time spectra

fusion from resonantly formed ddμ (bfastcomponent) was reduced in ortho-D2

Page 13: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Result on ortho-para D2 μCFNormal D2 and Ortho-D2

Large effects (ddμ formation rate) were observed![A. Toyoda(2000) in Phys.Rev.Lett.24, 243401(2003) fusion protonsH. Imao(2004) in EXA-05, MSI-05 fusion neutrons]

Theoretical calculations agreed only with the gas result (15% increase in ortho-D2)The effect was opposite to theory in liquid and solid D2.

Page 14: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

To understand the resultFor gas, the result was consistent with calculations based on idealistic non-interacting D2

Inversion in liquid/solid is key to understanding effect of condensed matter in μCFTheories are under development.

energy shift, broadening(still it is difficult to change the order of resonance in ortho/para)

phonon effect (solid only)New experimental run with ortho- and para-D2 for more temperature points(near liquid/gas boundary) is planned

Ki=0

2

Ki=3 4 2

10 20 300

~5K

~20K~50K

F=3/2

F=1/2

共鳴位置とMaxwell分布

共鳴エネルギー[meV]

(ortho)

(ortho)(para)

Page 15: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

What about dtμ: theoretical calculations1. Idealistic gas modeltμ + D2 [(dtμ)dee]low temp. resonance only for para-D2

2. with Condensed matter effectunder development [Adamczak]

Even larger effect of ortho-para D2

expected!

[Faifman]

23K liquid

Page 16: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Planned experiment and expected effect

Prepare ortho-D2 and para-D2 and mix with T2

Enhancement or reduction of μCF in pure mixture followed by1. molecular equilibration process

D2 + T2 2DT (~68 hour in D/T(50%))tµ + D2 [(dtµ)dee]tµ + DT [(dtµ)tee] (λdtµ

0,D2>>λdtµ0,DT)

2. ortho-para equilibration by radiation effecto-p conversion by paramagnetic T atom~16 hours in D/T(50%) at 14K

Cycling Rateλc = 1/(τd+τt)=1/[ q1sCd/(λdtCt) + (3/4)/(λtμ

1,0Ct)+ 1/(λ0dtμ-D2(o,p)CD2(o,p) + λdtμ

0,DT CDT)]

full eq.

av. time waiting dμ->tμ transfer

av. time in tμ(F=1) stateav. time before dtμ formation

λc

Time [hr]

Page 17: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Towards highest fusion yieldT2 mixture with ortho-D2 at liquid/solid condition best candidate for maximum fusion yield in μCF1) Faster cycling rate

high density φ (liquid, solid)faster dtμ formation rate

D2 para-rich (or ortho-rich)2) Smaller W

high density (liquid/solid) high reactivation after μα stickingW ~ 0.6%

Typical neutron yield in liquid D/T ~110/muonif λc=260Yn = λc/λn = 1/(λ0/φλc + W) = 1/(0.45/1.25*260+0.006)=140

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Preparation of ortho/para D2 gasOrtho D2 (established)

by ortho-para conversion with Al2O3/Cr2O3 catalysis

AnalysisRaman scattering spectroscopy

Para D2 (under study)selective absorption on Al2O3 at ~20K 99% para D2 is possible

D.A. Depatue and R.L. Mills, Rev. Sci. Instruments 39 (1968) 105

Para-to-Ortho Conversion

0

100

200

300

400

500

600

700

800

900

475 476 477 478 479 480 481 482 483 484 485

wavelength (nm)

coun

ts/4

0sec

normal

3hr

6hr

9hr

20hr

Our Target

ortho D2

normal D2

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µCF at RIKEN-RAL Muon Facility

RIKEN-RAL Muon at ISIS (1994~)Intense pulsed muon beam(70ns width, 50 Hz)800MeV x 200µA proton20~150MeV/c µ+/µ- muon5x104 µ-/s (55MeV/c)

µCF experiment

Proton beam line

µSR

Slow µ (Matsuda)

µA* (Strasser)

Page 20: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

µCF target and detectors

Cryogenic target : 1 c.c. liquid or solid D-TDetectors with calibration

fusion neutrons, X-rays, µe decay120 muon stops per pulse106 fusions/s

0 100mm

Muon

90 400

Neutron detectors

µe counters

D-T Target

Si(Li) X-ray detector

Be Windows

840

Superconducting magnet

~ ~

~ ~

~ ~ n

X-ray

μe

muonµCF setup

(RIKEN-RAL Port1)

Page 21: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

Other ongoing studies of μCFUnderstanding mechanism and parameters of key processes1. Muon-to-alpha sticking loss

muon-to-alpha sticking x-rays2. Muon loss to accumulated 3He from tritium decay

tHeμ molecule formation and decay3. dtμ formaiton in wider and exotic target conditions

low temperature solid D/T, high density D/T, ortho-para D2

4. fusion in ttμparticle correlations in 4He-n-n exit channel

Intense muon beams will definitely contribute to these study of μCF1) efficient search of more and more target conditions2) short-lived extreme conditions (laser, plasma etc)3) better S/N4) exotic beams from μCF5) intense neutron source

Page 22: Muon Catalyzed Fusion (μCF) - New progress and future planMuon Catalyzed Fusion (μCF) - New progress and future plan K. Ishida (RIKEN) Introduction New progress Muonic molecule formation

SummaryA clear effect of ortho-para ratio was observed for ddμ formation in D2, which is the most important rate limiting process in μCF.

Even larger effect (and enhancement) is predicted for dtμ formation

This opens up possibility for enhancement of μCFby controlling initial molecular states.