Muon Catalyzed Fusion CF

1
Muon Catalyzed Fusion (µCF)
NuFact02 4 July 2002 Imperial College, London

• K. Ishida (RIKEN)
• Principle of µCF
• Topics
• D2/T2 a-sticking, dtµ formation
• T2 tt-fusion, He accumulation
• µCF with high intensity muon beams
• in collaboration with
• K. Nagamine1,2, T. Matsuzaki1, S. Nakamura1,
  N. Kawamura1,
• Y. Matsuda1, A. Toyoda3, H. Imao3, M. Kato4,
  H. Sugai4, M. Tanase4,
• K. Kudo5, N. Takeda5, G.H. Eaton6
• 1RIKEN, 2KEK, 3U. Tokyo, 4JAERI, 5AIST, 6RAL
• present address KEK, U. Tohoku

2
Principle of Muon Catalyzed Fusion (µCF)

• 1.Muon injected in D2T2 mixture
• behaving like heavy electron
• 2.Coulomb barrier shrinks
• in small dtµ molecule
• (nuclear distance
• 1/200 of DT molecule)
• 3.Muon released after d-t fusion
• and find another d-t pair to fuse
• ?Muon working as catalyst
• of d-t fusion

3
µCF (Motivation)

• Exotic atoms and molecules
• atomic physics in small scale
• rich in few body problems
• dt fusion and alpha-sticking
• dtµ levels and formation
• atomic collisions, muon transfer
• cooperation between experiment and theory
• 4060 in µCF01 Conference
• Prospect for applications (fusion neutron source,
  fusion energy)
• muon production cost (5 GeV)
• vs
• fusion output (17.6 MeV x 200?)
• very close to breakeven

4
Maximizing µCF Cycle

• Observables
• (1) Cycling rate lc (?)(vs l0 muon life)
• rate for completing one cycle
• dtµ formation tµ D2 ?(dtµ)dee
• (2) Muon loss W (?)
• muon loss per cycle
• muon sticking to a-particle is the main loss
• Number of fusion per muon
• Yn f?c/?n 1/(?0/f?c)W (?)

5
Present status of µCF understanding

• dtµ molecule formation
• unexpectedly high dtµ formation rate (109 /s)
  was understood
• by Vesman mechanism of resonant molecular
  formation
• still many surprises
• density dependence
• low temperature solid state effect

6
Present status of µCF understanding

• am Sticking probability
• main source of muon loss from µCF cycle
• discrepancy between theory and experiments

7
Muon to alpha sticking and X-rays

• Main loss process of muons W ?s ...
• Ultimate obstacle for µCF(Yn lt 1/?s)
• Previous experiments determine W from
• fusion neutron and subtract possible other losses

Final Sticking(? neutron yield) ws (1-R)
ws0 Initial sticking ws0 ? dt-fusion in
dtm Reactivation R ? am (3.5MeV) atomic
process X-ray measurement Y(Ka) gKaws0, Y(Kb)
gKbws0 Direct measurement of initial sticking
ws0 am excited states and its time evolvement
(Kb/Karatio, Doppler width)
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µCF at RIKEN-RAL Muon Facility
Proton beam line

• RIKEN-RAL Muon at ISIS (1994)
• Intense pulsed muon beam
• (70ns width, 50 Hz)
• 800MeV x 200µA proton
• 20150MeV/c µ/µ- muon
• 105 µ-/s (55MeV/c)

Slow µ
µA etc
µSR
µCF experiment
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µCF Experiment at RIKEN-RAL

• Use of strong pulsed muon beam
• Tritium handling facility
• Detectors with calibration (fusion neutrons,
  X-rays)
• Stopping muon number(µe decay and µBe X-ray)
• Determine basic parameters and find the
  condition for improving efficiency
• ?c, W, X-ray emission
• ? a sticking probability and other loss
  processes
• reaction rates (dtµ formation rate, muon
  transfer etc)

10
Muon to alpha sticking

• Observation of x-rays from ma sticking under huge
  bremsstrahlung b.g.
• with intense pulsed muon beam at RIKEN-RAL
• Y(Ka),Y(Kb) Ka,Kb x-ray per fusion

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Measure neutron (effective sticking) and
aµX-ray (initial sticking) in the same experiment
12
Result of X-ray and neutron measurement

• Effective sticking ws (0.52) lt theoretical
  calculations (0.60)
• X-ray yield Yx(Ka) (0.27) calc.

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a-stiking

• Understanding the result
• (1) ionization from n?3 are much faster than
  radiative transition or
• (2) initial sticking to n?3 only is anomalously
  smaller (???)
• next step
• improving sticking x-ray data from ddm PSI,
  ttmRIKEN to compare reactivation effect

Ionization
ngt3
effective sticking ws 0.52 lt calc 0.6 ma Ka
X-ray Yx(Ka) 0.27 calc Y(Kb)/ Y(Ka) 7-1
ltltcalc(12)
0.09
n3
g
K
b
2p
0.03
2s
g
K
a
0.10
1S
Excita-
Deexcita-
0.68
tion
tion
Initial
am
Effective Sticking
Sticking
w
0
s
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Muon transfer to helium-3
µ
a
t

• (Another important loss process)
• (x3Heµ) (Xp,d,t) molecule formation
• (xµ) He -gt (xHeµ)
• theoretically predicted Popov, Kravtsov
• first observed in D24He KEK 1987
• then also in D23He KEK 1989
• and T23He RIKEN 1996
• formation rates
• radiative non-rad decay
• Kamimura, KEK/RIKEN
• fusion in d3Hem (Dubnaa, PSI)

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µCF in pure T2

• 1) tt-fusion at very low energy
• t t ?ann(Q14MeV)
• one neutron carries more energy
• than statistical dist.
• strong am correlation
• (5He resonance state)
• 2) t3Heµ decay mode etc
• radiative decay branch
• (competition with particle decay)
• 20 d3Heµ
• 50 d4Heµ
• gt90 t3Heµ
• 3) sticking from ttµ fusion

t3Heµ
am Ka
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dtµ, ddµ formation (Nonequilibrium and
ortho/paraeffect)

• Effect of D2, DT, T2 molecular composition
• in dtµ-formation
• tµ D2 -gt (dtµ)dee
• tµ DT -gt (dtµ)tee
• D2 T2 ? 2DT proceeds gradually (56 hours at
  20K) after DT mixture
• gradual decrease of fusion neutron yield
• ?dtµ0,D2/2 208 µs-1 (200 _at_ psi)
• ?dtµ0,DT 94 µs-1 (10 _at_ psi) (preliminary!)
• Ortho-para effect(at RAL TRIUMF)
• Toyoda, Ishida, Nagamine
• Ortho D2(J0,2,..) normal D2(orthopara21)
• dµ D2 -gt (ddµ)dee fusion proton
• Ortho vs normal 1530 reduction in ddµ
  formation
• first indication of ortho-para effect
• Opposite to a simple theory based on gas model

D2T2
D2T2DT
?c
E2(E-?E)
d
p
µ
E1(?E)
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µCF by other groups

• PSI
• strongest muon beam
• fusion neutron, ion chamber, X, g, ...
• TRIUMF
• thin solid layer target, energetic dµ, tµ
• Dubna
• fusion neutron, high temperature, high pressure,
  H/D/T mixture
• LAMPF
• fusion neutron, high temperature, high pressure

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µCF and exotic atoms Conferences

• International Conference on mCF
• 22-26 April, 2001 (Shimoda, Japan) was hosted by
  RIKEN
• 100 participants
• following Tokyo (1986), Leningrad(1987),
• Florida(1988), Oxford(1989), Wien(1990),
• Uppsala (1993), Dubna (1995), Ascona (1998)
• there will be EXA02 in Wien in Nov

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µCF with High Intensity Muon Beam

• 1)Measurement and control of µCF with expanded
  target condition
• (dtµ formation, a sticking)
• high temperature, high density D/T target
• naturally more µCF expected
• plasma (reducing dE/dx)
• atomic and molecular states
• (vibrational rotational levels by laser,
  ortho-para)

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µCF with High Intensity Muon Beam

• 2)Precise measurement of X-rays
• with improvement of beam, detectors, and target
  system
• 1) X-ray intensity ratio(Ka, Kb, Kg, L)
• transition between levels
• 2) Doppler shift
• aµ velocity(dE/dx)
• 3) 2keV dµ, tµ Ka X-rays
• q1s problem, radiationless transition
• Detectors
• pileup ? segmentaiton (Ge ball, Strip Si)?flash
  ADC
• energy resolution ?diffraction spectrometer,
  calorimeter
• low energy(2keV) ?thin window(or solid layer)
• Intense muon beam
• sharp and monochromatic beam -gt good S/N ratio

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MuCF with High Intensity Muon Beam

• 3) exotic (am) beam extraction and interaction
• For systematic study of atomic process and
  stopping power (dE/dx)
• to solve am sticking mystery
• Atomic collision of (am) was estimated
• only by scaling from normal atomic collision
• or purely by theoretical calculation
• we can measure
• reactivation?excitations (X-rays)
• Estimation of (am) beam yield at RIKEN-RAL
• 1000 m stop in (5cm x 5cm x 4 mg/cm2)
• X 20 fusion/m (?)
• X 0.01 (sticking) X 0.01 (spectrometer)
• 2 /sec (am) of 3.5MeV energy

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Exotic beams with µCF

• 4) applications of µCF
• keV µ- beam
• extract 10keV µ- released after dt-fusion
• K. Nagamine, P. Strasser

solid D/T
keV µ- collector
incoming muons
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µCF with High Intensity Muon Beam

• 5) Applications of µCF
• Intense fusion neutron source

MUCATEX-ENEA design
d beam
D-T target
production target
irradiated materials
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µCF with High Intensity Muon Beam

• 6) µCF for power generation

K. Nagamine
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Summary

• with High Intensity Muon Source
• further understanding of basic processes
• precise X-ray measurement
• towards break-even with extreme target
  conditions
• more exotic beams (aµ beam, slow µ- etc)
• generation of fusion neutrons power