Electron Screening in deuterated targets ©Francesco Raiola Raiola Francesco, Fakultät für Physik und Astronomie Ruhr-Universität Bochum, D Bochum, Germany Ruhr-Universität Bochum (Germany) Lehrstuhl für Physik mit Ionenstrahlen (EP. III) 01.October.2002 Debrecen

Electron Screening laboratory nuclear reaction: ions atoms/molecules (projectile) (target) (U e << E) E + U e U e  Z 1 Z 2 e 2 /R a E bare screened Potential V(r) RnRn RtRt EcEc 0 RaRa r electronic cloud enhancement of cross section f lab =  s (E)  b (E)  exp  U e E

D(d,p)t reaction in gas target in deuterated-metal target U e = 25 ± 5 [eV] (from U. Greife et al. (1995) work) U ad = 14 [ev] (  factor 2 is not yet understood!!) Russian group (1998) Berlin group (2001) Bochum group ( ) (in progress) offset  Bochum (1995) screening in gasscreening in metals >

d(d,p)t p t sample spectrum at E d =48 keV set-up at Bochum Si Ni foil 0,75 µm Ni aperture 4 mm  x/y – scanners deuteron beam metallic target Cu pipe -200 V Si liquid-nitrogen-cooling turbo pump 450 l/s  = 130° P = 2x10 -8 mbar

ERDA range (E d =100 keV) Ta foil bombarded with 10 keV deuterons saturation production of deuterated Ta

E [keV] Data U e = 340±14 [eV] bare differentiation thin-target data F.Raiola et al., Eur. Phys. J. A13(2002)377

RBS (Rutherford Backscattering Spectrometry) Al O S(E) [keV b] Al 2 O 3 Al U e  30 [eV] U e =520 ± 50 [eV]

Present results Element Z U e [eV] Stoichiometry x Be4170 ± 4012,5 B5  30 2,6 CbCb 652 ± 203,1 Mg12440 ± 408,7 Al13520 ± 503,8 Si b 1445 ± 204,3 Sc21……,,,,, Ti22  30 0,8 V23350 ± 3016,0 Cr24220 ± 207,8 Mn25350 ± 403,7 Fe26450 ± 5013,0 Co27201 ± 203,1 Ni28450 ± 8026,0 Cu2943 ± 206,6 Zn30 Ge b 3260 ± 201,8 Sr38…….….. Y39320 ± 408,3 Zr4083 ± 200,4 Nb41400 ± 408,7 Mo42220 ± 207,0 Ru44220 ± 305,6 Rh45840 ± 7011,0 Pd46800 ± 7035,0 Ag4723 ± 1010,0 Cd48390 ± 606,2 Sn50200 ± 2036,0 Er c 68  50 1,0 Yb c 70  40 0,8 Hf7287 ± 200,6 Ta a ± 409,1 W74220 ± 203,3 Re75700 ± 70….. Ir77330 ± 304,4 Pt78440 ± 5014,0 Au7961 ± 202,6 Tl81300 ± 4035,0 Pb82440 ± 5018,0 a From F.Raiola et al., Eur. Phys. J. A13(2002)377 b Insulators c Lanthanoids

Summary Large screening effect: all metals except in the noble metals (Cu, Ag, Au) Low screening effect: all insulators as well as deuterated metals having a small x value (x  1.0) not a solution stopping power thermal motion Channeling effect diffusion conductivity crystal structure electron configuration Fermi shuttle acceleration mechanism