Muon Catalyzed Fusion (µCF) K. Ishida (RIKEN) Principle of µCF Topics D2/T2 α-sticking, dtµ formation T2tt-fusion, He accumulation µCF with high intensity muon beams in collaboration with K. Nagamine 1,2 *, T. Matsuzaki 1, S. Nakamura 1 **, N. Kawamura 1 *, Y. Matsuda 1, A. Toyoda 3*, H. Imao 3, M. Kato 4, H. Sugai 4, M. Tanase 4, K. Kudo 5, N. Takeda 5, G.H. Eaton 6 1 RIKEN, 2 KEK, 3 U. Tokyo, 4 JAERI, 5 AIST, 6 RAL present address *KEK, **U. Tohoku NuFact02 4 July 2002 Imperial College, London

Principle of Muon Catalyzed Fusion (µCF) 1. Muon injected in D 2 +T 2 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

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 ~40%:60% 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

Maximizing µCF Cycle Observables (1) Cycling rate c （ ↑ ） (vs 0: muon life) rate for completing one cycle dtµ formation tµ + D2 →[(dtµ)dee] (2) Muon loss W (↓ ） muon loss per cycle muon sticking to  -particle is the main loss Number of fusion per muon Yn = φλc/λn = １／ [(λ 0 /φλ c )+W] （ ↑ ）

Present status of µCF understanding dtµ molecule formation unexpectedly high dtµ formation rate (10 9 /s) was understood by Vesman mechanism of resonant molecular formation still many surprises density dependence low temperature & solid state effect

Present status of µCF understanding  Sticking probability main source of muon loss from µCF cycle discrepancy between theory and experiments  n free muon (~10keV) initial sticking:  thermalized  effective sticking:  s =(1-R)  s 0 reactivation 3.5MeV 14.1MeV  -  - R~0.35  s 0 ~0.9%  s 0 : Theory  s : Theory

Muon to alpha sticking and X-rays Main loss process of muons W = ω s +... Ultimate obstacle for µCF （ Yn < 1/ω s ) Previous experiments: determine W from fusion neutron and subtract possible other losses Final Sticking （ ← neutron yield ）  s = (1-R)  s 0 Initial sticking  s 0 ← dt-fusion in dt  Reactivation R ←  (3.5MeV) atomic process X-ray measurement Y(K  ) =  Ka  s 0, Y(K  ) =  K   s 0 Direct measurement of initial sticking  s 0  excited states and its time evolvement （ K  /K  ratio, Doppler width)

µCF at RIKEN-RAL Muon Facility RIKEN-RAL Muon at ISIS (1994~) Intense pulsed muon beam (70ns width, 50 Hz) 800MeV x 200µA proton 20~150MeV/c µ + /µ - muon 10 5 µ - /s (55MeV/c) µCF experiment Proton beam line µSR Slow µ µA* etc

µ CF Experiment at RIKEN-RAL Use of strong pulsed muon beam Tritium handling facility Detectors with calibration (fusion neutrons, X-rays) Stopping muon number( µ e decay and µ Be 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 (dt µ formation rate, muon transfer etc)

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  ):  x-ray per fusion

Measure neutron (effective sticking) and αμX-ray (initial sticking) in the same experiment

Result of X-ray and neutron measurement M. Kamimura (EXAT98)  s 0 Increased Ionization PSI-87 PSI-84 LAMPF-92 PSI (Ct=0.04%) RIKEN-RAL Theories ~’88 Effective sticking  s (0.52%) < theoretical calculations (0.60%) X-ray yield Y x (Ka) (0.27%) ~ calc.

 -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 dd  [PSI], tt  [RIKEN] to compare reactivation effect Excita- tion Deexcita- tion Ionization 1S n=3 n>3 Initial Sticking   K   s % 0.10% 0.03% 2p 2s 0.09%  K  Effective Sticking effective sticking  s =0.52 ％ < calc 0.6 ％  X-ray Y x (Ka) 0.27 ％ ~ calc Y(K  )/ Y(K  ) =7+-1% <<calc(12%)

Muon transfer to helium-3 (Another important loss process) (x 3 Heµ)* (X=p,d,t) molecule formation (xµ) + He -> (xHeµ) theoretically predicted [Popov, Kravtsov] first observed in D He [KEK 1987] then also in D He [KEK 1989] and T He [RIKEN 1996] formation rates radiative & non-rad decay [Kamimura, KEK/RIKEN] fusion in d 3 He  (Dubnaa, PSI)  t µ

µCF in pure T 2 1) tt-fusion at very low energy t + t →α+n+n(Q=14MeV) one neutron carries more energy than statistical dist. strong  correlation ( 5 He resonance state) 2) t 3 Heµ decay mode etc radiative decay branch (competition with particle decay) ~20% d 3 Heµ ~50% d 4 Heµ >90% t 3 Heµ 3) sticking from ttµ fusion t 3 Heµ 

dt µ, dd µ formation (Nonequilibrium and ortho/paraeffect) Effect of D 2, DT, T 2 molecular composition in dtµ-formation tµ + D 2 -> [(dtµ)dee] tµ + DT -> [(dtµ)tee] D 2 + T 2 ⇄ 2DT proceeds gradually (~56 hours at 20K) after D+T mixture gradual decrease of fusion neutron yield λ dtµ 0,D2 ／ 2 = 208 µs -1 psi) λ dtµ 0,DT = 94 µs -1 psi) (preliminary!) Ortho-para effect （ at RAL & TRIUMF ） [Toyoda, Ishida, Nagamine] Ortho D2 (J=0,2,..) & normal D2 (ortho:para=2:1) dµ + D 2 -> [(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 λc D2+T2 D2+T2+DT p d µ E1(ΔE) E2(E-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 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

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 µ CF 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 with improvement of beam, detectors, and target system 1) X-ray intensity ratio （  L) transition between levels 2) Doppler shift αμ velocity （ dE/dx ） 3) 2keV d µ, t µ 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  

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/cm 2 ) X 20 fusion/  (?) X 0.01 (sticking) X 0.01 (spectrometer) = 2 /sec (  ) + of 3.5MeV energy

Exotic beams with µCF 4) applications of µCF keV µ- beam extract 10keV µ - released after dt-fusion [K. Nagamine, P. Strasser] keV µ - collector incoming muons solid D/T

µCF with High Intensity Muon Beam 5) Applications of µCF Intense fusion neutron source MUCATEX-ENEA design d beam production target D-T target irradiated materials

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