Transcript Muon Catalyzed Fusion (µCF) K. Ishida (RIKEN)

NuFact02 4 July 2002 Imperial College, London
Muon Catalyzed Fusion (µCF)
K. Ishida (RIKEN)
Principle of µCF
Topics
D2/T2 α-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
Principle of Muon Catalyzed Fusion (µCF)
1.Muon injected in D2+T2 mixture
behaving like heavy electron

2.Coulomb barrier shrinks
in small dtµ molecule
-
3He
(nuclear distance ~
1/200 of DT molecule)
d
3.Muon released after d-t fusion
and find another d-t pair to fuse
→Muon working as catalyst
of d-t fusion
tt
t
cost for
muon
production
~5.3 GeV
injected
muon
t
muonic atom
formation
(~10 -11 s)
free
muon
muonic
molecule
formation
muon
transfer
d

(~5x10 -9 s)
(~5x10 -9s)
composit
molecule
3He


dd
d dt
recycle
(~99.5%)
14MeV
neutron
reactivation
(R~0.35)

K/K 
X-ray
 sticking
s0~0.9%

nuclear
fusion
(~10-12 s)
n

17.6MeV x ?
energy output
µCF (Motivation)
transfer
3He to He
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
~40%:60% in µCF01 Conference
t
d
injected
muon

d
14MeV
neutron
K/K

X-ray
effective
sticking
s=(1-R)s0

n

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
dtµ
formation
dt
nuclear
fusion
17.6MeV x Yn
energy output
Maximizing µCF Cycle
transfer
3He to He
Observables
t
(1) Cycling rate lc （↑）(vs l0: muon life)
rate for completing one cycle
dtµ formation tµ + D2 →[(dtµ)dee]
(2) Muon loss
d
injected
muon

d
W (↓）
14MeV
neutron
muon loss per cycle
K/K

X-ray
muon sticking to -particle is the main loss effective
sticking
Number of fusion per muon
s=(1-R)s0
Yn = φλc/λn = １／[(λ0/φλc)+W]
dtµ
formation
（↑）

n

dt
nuclear
fusion
17.6MeV x Yn
energy output
Present status of µCF understanding
dtµ molecule formation
unexpectedly high dtµ formation rate (109 /s) was understood
by Vesman mechanism of resonant molecular formation
t + (D2)iKi → [(dt)11dee]*vfKf
still many surprises
eedt
d
d →

density dependence
＋

t
eelow temperature & solid state effect
dt
U
d
0t
=2
R
11dt
J,v=(1,1)
E 
=1
~0.3eV
=0
=0
D2
J, = (0,0)
E  = 11dt
[(dt)dee]
+ 0t
Present status of µCF understanding
 Sticking probability
main source of muon loss from µCF cycle
discrepancy between theory and experiments
n
free muon(~10keV)
14.1MeV
s0~0.9%
initial sticking:
3.5MeV

thermalized 
0
s :Theory

R~0.35
effective sticking:
s :Theory
s=(1-R)s0
reactivation
Muon to alpha sticking and X-rays
Main loss process of muons W = ωs + ...
Ultimate obstacle for µCF（Yn < 1/ωs)
Previous experiments: determine W from
fusion neutron and subtract possible other losses
Ionization
Reactivation:
R
~ 0.35
n>3
0.09%
n=3
2p
2s
0.03%
0.10%
1S
Excita- Deexcitation
tion
0.68%
Initial
Sticking
s
0

Initial sticking s0 ← dt-fusion in dt
Reactivation R ←  (3.5MeV) atomic
process
X-ray measurement
Y(K) = Kas0, Y(K) = Ks0
K
K
Final Sticking（← neutron yield）
s = (1-R) s0
d, t
Transfer
Thermalization
Effective Sticking
s = (1-R) s0
Direct measurement of initial sticking s0
 excited states and its time evolvement
（K/Kratio, Doppler width)
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
20~150MeV/c µ+/µ- muon
Slow µ
105 µ-/s (55MeV/c)
µA* etc
µSR
µCF experiment
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
λc, Ｗ, X-ray emission
→ α sticking probability and other loss processes
reaction rates (dtµ formation rate, muon transfer etc)
400
µe
counters
840
~
~
~
~
90
Be
Windows
Si(Li) X-ray
detector
~
~
Superconducting
magnet
Muon
D-T
Target
Neutron detectors
0
100mm
Muon to alpha sticking
Observation of x-rays from  sticking under huge bremsstrahlung b.g.
with intense pulsed muon beam at RIKEN-RAL
Y(K),Y(K): K,K x-ray per fusion
d.c. muon beam
Brems b.g.
time
pulsed muon beam
gate
20µs
time
20ms
Measure
neutron (effective sticking)
and
αμX-ray (initial sticking)
in the same experiment
Result of X-ray and neutron measurement
RIKEN-RAL
Increased
Ionization
PSI
(Ct=0.04%)
PSI-87
PSI-84
LAMPF-92
Effective sticking s (0.52%) < theoretical
calculations (0.60%)
X-ray yield Yx(Ka) (0.27%) ~ calc.
Theories
~’88
M. Kamimura
(EXAT98)
s0
-stiking
Understanding the result
(1) ionization from n≧3 are much faster than radiative transition
(2) initial sticking to n≧3 only is anomalously smaller (???)
next step
improving sticking x-ray data from dd [PSI],
tt[RIKEN] to compare reactivation effect
or
Ionization
n>3
0.09%
0.03%
n=3
2p
2s
0.10%
0.68%
Y(K)/ Y(K) =7+-1%
K
<<calc(12%)
1S
Excita- Deexcitation
tion
Initial
Sticking
s0
 K

effective sticking s =0.52％
< calc 0.6％
 K X-ray Yx(Ka) 0.27％
~ calc
Effective Sticking
Muon transfer to helium-3
(Another important loss process)
(x3Heµ)* (X=p,d,t) molecule formation
(xµ) + He -> (xHeµ)
theoretically predicted
[Popov, Kravtsov]
first observed in D2+4He [KEK 1987]
then also in D2+3He [KEK 1989]
and T2+3He [RIKEN 1996]
formation rates
radiative & non-rad decay
[Kamimura, KEK/RIKEN]
fusion in d3He (Dubnaa, PSI)
µ

t
µCF in pure T2
1) tt-fusion at very low energy
t + t →α+n+n(Q=14MeV)
one neutron carries more energy
than statistical dist.
strong  correlation
(5He resonance state)
2) t3Heµ decay mode etc
radiative decay branch
(competition with particle decay)
~20% d3Heµ
~50% d4Heµ
>90% t3Heµ
3) sticking from ttµ fusion
t3Heµ
 K
dtµ, ddµ formation (Nonequilibrium and ortho/paraeffect)
Effect of D2, DT, T2 molecular composition
in dtµ-formation
tµ + D2 -> [(dtµ)dee]
tµ + DT -> [(dtµ)tee]
D2 + T2 ⇄ 2DT proceeds gradually (~56 hours at 20K) after D+T mixture
gradual decrease of fusion neutron yield
λdtµ0,D2／2 = 208 µs-1 (200 @ psi)
λdtµ
0,DT
= 94
µs-1
(~10 @ psi) (preliminary!)
D2+T2
D2+T2+DT
λc
Ortho-para effect（at RAL & TRIUMF）
[Toyoda, Ishida, Nagamine]
dµ + D2 -> [(ddµ)dee] fusion proton
Ortho vs normal: 15~30% reduction in ddµ formation
first indication of ortho-para effect
Opposite to a simple theory based on gas model
E2(E-ΔE)
Ortho D2(J=0,2,..)& normal D2(ortho:para=2:1)
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d
µ
p
E1(ΔE)
µCF by other groups
PSI
strongest muon beam
fusion neutron, ion chamber, X, , ...
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
µCF and exotic atoms Conferences
International Conference on CF
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,  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)
µCF with High Intensity Muon Beam
２）Precise measurement of X-rays
 K
with improvement of beam, detectors, and target system
1) X-ray intensity ratio（K, K, K, L)
transition between levels
2) Doppler shift
αμ velocity（dE/dx）
3) 2keV dµ, tµ K 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 -> good S/N ratio
K
MuCF with High Intensity Muon Beam
3) exotic ()+ beam extraction and interaction
For systematic study of atomic process and stopping power (dE/dx)
to solve  sticking mystery
Atomic collision of ()+ was estimated
only by scaling from normal atomic collision
or purely by theoretical calculation
we can measure
reactivation、excitations (X-rays)
Estimation of ()+ beam yield at RIKEN-RAL
1000  stop in (5cm x 5cm x 4 mg/cm2)
X 20 fusion/ (?)
X 0.01 (sticking) X 0.01 (spectrometer)
= 2 /sec ()+ of 3.5MeV energy
()+
 ++
muon
D/T
reaction
and detection
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
電子検出器
keV µ- collector
keV負ミュオン発生装置
固相薄膜標的
高真空チェンバー
ke V 負
ン
ミュオ
スリット
イオン検出器
μＣＦ標的
磁場コイル
冷凍機
incoming
muons
ミュオンビーム
中性子検出器
Ｘ線検出器
µCF with High Intensity Muon Beam
5) Applications of µCF
Intense fusion neutron source
MUCATEX-ENEA design
D-T
target
production
target
irradiated
materials
d beam
µCF with High Intensity Muon Beam
6) µCF for power generation
[K. Nagamine]
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 (µ beam, slow µ- etc)
generation of fusion neutrons & power