H.M. MENU 2010 Williamsburg1 1  bound states in nuclei Hartmut Machner (FZ Jülich & University Duisburg-Essen) GEM collaboration Outline Why are  -mesic nuclei interesting? Search via production experiments Search via Two Body Final State Interaction (FSI) p+d  + 3 He tensor pol. d+d  p+ 6 Li  7 Be

H.M. MENU 2010 Williamsburg2 Heuristic approach   A rather large s-wave  -nucleon scattering length lead to the idea of bound  -nucleus systems.   This would be a strong bound system, contrary to pionic atoms (Coulomb bound).   How to observe?   Recoil free transfer reactions like in hyper-nuclei and in pionic atoms cases.   Nuclear projectiles:   d+A  3 He+[(A-1)  ]:   Break up protons have same magnetic rigidity as 3 He’s.    Large cross section.   p+A  3 He+[(A-2)  ]:   Magnetic rigidity of beam particles differ by a factor of two from 3 He’s.   Small cross section. 

H.M. MENU 2010 Williamsburg3 Missing mass spectroscopy emitted particle Incident particle target meson deuteron-hole Momentum transfers for  -mesic nuclei formation

H.M. MENU 2010 Williamsburg4 Previous searches Pfeiffer et al. PRL:  + 3 He  0 +p+X, 3.5  Sokol et al.:  + 12 C  + +n+X; Both ejectiles are anti-correlated; =300 MeV, =100 MeV Lieb et al. (  +,p) Chrien et al. PRL q=200 MeV/c inclusive

H.M. MENU 2010 Williamsburg5 Reactions 3 He in BIG KARL, carries the full beam momentum  -p almost back to back in ENSTAR 3-fold coincidence + 3 more constraints!

6 Big Karl & ENSTAR

H.M. MENU 2010 Williamsburg7 Proton + Aluminium target Particle identification with BK focal plane detectors (high threshold cuts light particles) Event of interest:  Two correlated particles: 5+4=9 fold coincidence  Pion leaves the detector: outer layer fires  Proton stopped in the middle layer NIM A 596 (08) 31 p 

8 Time- and 3 He spectra

H.M. MENU 2010 Williamsburg9  bump) = 50 pb ε branch = 1/3 L.-C. Liu expected: 5-22 nb Cross section

H.M. MENU 2010 Williamsburg10 Results PRC 70 (2009) (R)

Quasi-bound requires: Im(a  A ) > 0 from unitarity |Im(a  A )| < |Re(a  A )| to have a pole in the negative energy half plane Re(a  A ) < 0 to have a bound state, but |FSI| 2  Re(a  A ) 2 |Q 0 (  3 He)|<|Q 0 (  4 He)| )|<|Q 0 (  7 Be)| Otherwise: virtual (unphysical) state 11 Two body final state interaction Tacid assumption: s-wave, and then d  /d  =  /4 

12 Excitation function:dp→ 3 He   2 /n free =0.82 T. Mersmann et al., PRL 98 (07)

H.M. MENU 2010 Williamsburg13 dd  Eur. Phys. J. A 26 (2005) 421

H.M. MENU 2010 Williamsburg14 Excitation Function Same momentum range as in p+d, but less data points. Cross section less than 5%! How to extract s-wave? Use tensor polarized beam!

H.M. MENU 2010 Williamsburg15 H. M., Mumbai, Febr Final result NP A 821 (2009) 193 PWA spin ampl.

scatt. length effective range H.M. MENU 2010 Williamsburg 16 Final result spin ampl.partial wave ampl.

H.M. MENU 2010 Williamsburg17 p+ 6 Li  + 7 Be 11 MeV above threshold g.s.+0.43MeV (L=1) previous exp. 4 states (L=1+L=3) p+ 6 Li  +X

Result

Subtraction of L=3 yield Al Khalili et al.: Upadhyay et al.: plus rescattering

H.M. MENU 2010 Williamsburg 20 Summary:  Search for -mesic nuclei employing recoil free kinematics.  We see an enhancement in the spectra after detecting 3 final particles: 3 He at small angles and  - +p back to back.  25 Mg  bound state: BE13 MeV, FWHM10 MeV  5 effect  We have measured angular distributions of cross sections and tensor analysing power for the reaction dd at 16.6 MeV above threshold  s-wave strength could be extracted  s-wave strength of other experiments (Willis et al., Wronska et al.) extracted  FSI shows Im a () = 0.0(5) fm. This indicates a small absorption because the nucleons are strongly bound  Not enough data for + 7 Be to say something  The -nucleus levels in heavy nuclei thus might be fairly narrow.

M. Abdel-Bary a, S. Abdel-Samad a, A. Budzanowski d, A. Chatterjee i, J. Ernst g, P. Hawranek a,c, R. Jahn e, V. Jha i, S. Kailas i, K. Kilian a, Da. Kirilov a,h, Di. Kirilov h, S. Kliczewski d, D. Kolev f, M. Kravcikova m, T. Kutsarova e, M. Lesiak a,c, J. Lieb j, H. Machner a, A. Magiera c, G. Martinska l, H. Nann k, N. Piskinov h, L. Pentchev e, D. Protic a, J. Ritman a, P. von Rossen a, B. J. Roy i, P. Shukla i, R. Siudak d, I. Sitnik h, M. Ulicny a,l, R. Tsenov f, J. Urban l, G. Vankova a,f, C. Wilkin n, G. Wüstner b a. Institut für Kernphysik, Forschungszentrum Jülich, Jülich, Germany b. Zentrallabor für Elektronik, Forschungszentrum Jülich, Jülich, Germany c. Institute of Physics, Jagellonian University, Krakow, Poland d. Institute of Nuclear Physics, Pan, Krakow, Poland e. Institute of Nuclear Physics and Nuclear Energy, Sofia, Bulgaria f. Physics Faculty, University of Sofia, Sofia, Bulgaria g. Institut für Strahlen- und Kernphysik der Universität Bonn, Bonn, Germany h. LHE, JINR, Dubna, Russia i. Nuclear Physics Division, BARC, Bombay, India j. Physics Department, George Mason University, Fairfax, Virginia, USA k. IUCF, Indiana University, Bloomington, Indiana, USA l. P. J. Safarik University, Kosice, Slovakia m. Technical University, Kosice, Kosice, Slovakia n. Department of Physics & Astronomy, UCL, London, U.K. H.M. MENU 2010 Williamsburg21 The GEM Collaboration

H.M. MENU 2010 Williamsburg22 Thank you for your attention

H.M. MENU 2010 Williamsburg23 FSI

H.M. MENU 2010 Williamsburg24

H.M. MENU 2010 Williamsburg25 Polarised beam dp elastic scattering

H.M. MENU 2010 Williamsburg26 Better fit than partial wave amplitudes (s, p, 2d waves), because less parameters (4 instead of 7) Angular dependence due to s-d interference

H.M. MENU 2010 Williamsburg27 ENSTAR detector