NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS

1. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS A Detailed Study of the 10,11B(d,α) and 10,11B(d,p)Reactions at Detector Angles between 135 and 170 degrees for the Energy Range Ed,Lab=900-2000 keV M. Kokkoris1, C. T. Papadopoulos1, R. Vlastou1, P. Misailides2, S. Harissopulos3, A. Lagoyannis3 1 Department of Physics, National Technical University of Athens, Zografou Campus 157 80, Athens, Greece 2 Department of Chemistry, Aristotle University, GR-54006, Thessaloniki, Greece 3 Institute of Nuclear Physics, TANDEM Accelerator, N.C.S.R. ‘Demokritos’, Aghia Paraskevi 153 10, Athens, Greece

2. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS • TOPICS: • MOTIVATION • EXPERIMENTAL SETUP AND PROCEDURE • ANALYSIS AND DISCUSSION • CONCLUSIONS • FUTURE PERSPECTIVES

3. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS • Nuclear Reaction Analysis (NRA) is well established as one of the primary methods in ion beam analysis of light elements in complex matrices. Other techniques are RBS and NBS. Main NRA advantages: (a) high isotopic selectivity, (b) good sensitivity for many nuclides (c) least destructive depth profiling, (d) accurate quantitative analysis and (e) possible simultaneous analysis of multiple light elements. • Main Problem: Lack of differential cross section data for a variety of beam-target combinations in literature • Ion Beam Analysis Nuclear Data Library: IBANDL • Analytical algorithms e.g. SIMNRA, RUMP etc. MOTIVATION:

4. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS 2. The ‘boron problem’: RBS is weak, NBS can be applied only in certain cases (no other light elements present, no high-Z matrix, very case-specific measurements): Ep=2.6 MeV 5% B in Si Eα=2.9 MeV Overlapping resonances (borax) PIGE + resonant PIGE not promising, NRA reactions proposed so far: (p,α), (α,p), (d,α): Very limited literature, cross sections of the order of ~1-10 mb/ster

5. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS Proposal: Implementation of the d-induced reactions in boron isotopes which are also sensitive to many light elements (16O, 12C, 14N, 19F) and can be applied in any accelerator setup (low beam energies required) Great possible technological implications (plasma physics, semiconductor industry, boron nitride films, environmental applications etc.) 3. Theoretical considerations: 1. Reaction Mechanism involved. 2. Broad resonances with overlapping widths. 3. Effect of electric charge asymmetry of the deuteron. 3. Multiple open channels, (d,d), (d,p), (d,α), (d,n)! 4. 8Be breakup channel.

6. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS 5.5 MV HV Tandem Accelerator, N.C.S.R. ‘Demokritos’ Motor driven goniometer Great angular accuracy (0.01 deg.) EXPERIMENTAL SETUP: * A.Pakou et al. , Phys. Rev. Lett. 90 (2003)

7. 8-16 single SSB, or 4-8 ΔE/E solid state detector telescopes for particle identification (depending on the reaction studied), associated with standard NIM or CAMAC electronics. Upgrading is scheduled. • The current setup allows for target cooling with water or methanol through a closed circuit during acquisition • Voltage suppression up to 1000 V on the collimator, target and/or faraday cup.

8. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS EXPERIMENTAL PROCEDURE: • Preparation/testing of the targets. • Spectra acquisition (45 energies between 900 and 2000 keV, 25 keV step) at variable charge, depending on statistics for both reactions. • Determination of the solid angle using an uncalibrated Am-Pu-Cm α-source + RBS spectra. Uncertainty in Q*Ω < 2.5(4.3)% due to voltage suppression and effective faraday cup (tested with Al and Au foils in the past). • Peak analysis using two different algorithms to account for the bias error (σ Yield(exp)<1% using Spectr and Origin). • Error evaluation: 1. Monitoring of the changes in the foil thickness (A in at/cm2) by sputtering and accuracy in the energy due to carbon buildup (despite the two liquid nitrogen traps). • Measurements with and without absorber foils.

9. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS ANALYSIS AND DISCUSSION:

10. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS • The excitation energy range reported, is important for the study of the influence of the resonance mechanism. The only strong influence reported in the past concerns the 11B(d,α)9Be reaction at Ed=1.85 MeV. Broad maxima have also been reported concerning the 10B(d,α)8Be reaction around Ed=1 and 2 MeV. The 10,11B(d,p) reaction cross sections on the other hand, seem to vary smoothly with energy (for the Ed range under study). • CIRE (GANIL) has been used for 2 or 3-body kinematics. • 10B enriched targets exist (94%) on Ta backings, d = 21.50.5 μg/cm2,11B or natB ones not yet (on thin Au foil?)

11. α+10B n+11C α+11B p+12B p+11B α+9Be α+8Be n+12C 12C 13C

12. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS CONCLUSIONS: • The study of the deuteron induced reactions in the boron isotopes will proceed via separate stages (for 10B and 11B respectively). • With the exception of the 11B(d,p)12B reaction, all the other reactions seem to be well suited for IBA applications. • The study of the 10B(d,p)11B reaction at backscattering angles might enhance NRA capabilities.  FIRST EXPECTED DETAILED EXPERIMENTAL STUDY OF THESE REACTIONS FOR NRA PURPOSES.

13. NATIONAL TECHNICAL UNIVERSITY OF ATHENS DEPARTMENT OF PHYSICS FUTURE PERSPECTIVES: • Many open questions: Angular distribution at forward angles? • What is the maximum analyzing depth? All the (d,p) and (d,α) reactions in light elements also need to be studied. Study of 14N, 19F as well as 32S,in progress using the same technique. • Time-consuming studies affect quick quantification of the results. • Completing the 12C(d,p1,p2,p3) analysis, after the natC(d,d0) and 12C(d,p0) in the same energy and angular range. • (d) Need for experimental data! – Extensive program scheduled for 3 years in order to supply the scientific community with benchmark data suitable for technological applications.