1. B.MOUGINOT IPNO PHD director : F. AZAIEZ, S. FRANCHOO Giant Pairing Vibration : Experimental Overview

2. Ground State 0 + First 0+ excited stateA Higher excited 0 + Next Major Shell Giant Pairing Vibration GPV Mode : Collective Excitation of Pair in the Next Major Shell Low-lying 0+ Excitation How to populate a O+ state in Nuclei ?

3. >Pairing vibrations : L=0 >Sensitive to Pairing interaction Giant Pairing Vibrations GPV GPV is a Collective mode > Should lie at high excitation energy > 2 nucleon transfer channel selective for pairing vibration ex (p,t) reaction E. Khan PRC69(2004)

4. Overview of (p,t) reactions Orihara Phys.Rev. C 9(1974)266 Data recorded at 8°- 65° 51.9MeV protons at Institute of Nuclear Study Lanford Phys.Rev. C 16(1977)988 35MeV protons at MSU cyclotron : Data recorded at 6° 14° 30° E* range : 0 - 10 MeV E* range : 0 - 7 MeV 208 Pb (p,t) 206 Pb

5. Position sensitive chamber at the focal plane of the spectrograph >Data recorded at 7°- 35° Shepard Nucl.Phys. A 322(1979)‏ 40 MeV protons at Indiana University Cyclotron (IUCF)‏ Takahashi Phys.Rev.C 27(1983)‏ 51.9 MeV protons at Institute of Nuclear Study Tokyo University Array of 200 proportional counters at the focal plane of the spectrometer >Data recorded at 2°- 60° E* range : 0 - 6 MeV E* range : 0 - 5 MeV

6. Mihailidis Phys.Rev.C 64(2001)‏ Gerlic Phys.Rev. C 39(1989)‏ 168 MeV protons at K220 Orsay Synchrocyclotron Vertical-wire Drift Chamber at focal plane of K600 spectrometer Data recorded at 7°- 34° Data recorded at 2°- 18° 120 MeV protons at IUCF E* range : 0 - 12 MeV E* range : 0 - 7 MeV 208 Pb (p,t) 206 Pb

7. 40 MeV protons at University of Minnesota linear accelerator Bassani Phys.Rev. 139(1965)‏ 8 Plastic scintillators at the focal plane of the spectrometer Data recorded at 7°-30° 120 Sn (p,t) 118 Sn E* range : 0 - 11 MeV

8. 89MeV protons at IUCF Crawley et al. Phys.Rev. C 22(1980)‏ 42 MeV protons at Jefferson lab resistive-wire proportional counter at focal plane of Enge spectrometer 250 0 0 Crawley et al. Phys.Rev.Lett. 39(1977)33 Data recorded at 10°- 45° Data recorded at 15°- 45° E* range : 0 - 50 MeV E* range : 0 - 20 MeV 120,122 Sn (p,t) 118,120 Sn

9. Why revisit (p,t) reactions for GPV? On 208Pb : >51.9 MeV proton at 8°- 65° : Orihara Phys.Rev. C 9(1974)266 >35 MeV proton at 6° 18° 30° : Lanford Phys.Rev. C 16(1977)988 >40 MeV proton at 7°- 35°: Shepard Nucl.Phys. A 322(1979)‏ >51.9 MeV proton at 6° 18° 30°:Takahashi Phys.Rev.C 27(1983)‏ >168 MeV proton at 2°-18°: Gerlic Phys.Rev. C 39(1989)‏ >120 MeV proton at 7°-34°: Mihailidis Phys.Rev.C 64(2001)‏ On 120Sn : >40 MeV proton at 7°- 30° : Bassani Phys.Rev. 139(1965)‏ >42 MeV proton at 10°- 45°:Crawley et al. Phys.Rev.Let. 39(1977)33 >89MeV proton at 15°- 45°:Crawley et al. Phys.Rev. C 22(1980)‏ No experiment at the right angle and/or the right energy !! 0°or very near 0°& 60 MeV GPV predicted at 10-20MeV >wrong Energy Range

10. At iThemba (South-Africa) : 208 Pb(p,t) 206 Pb Q = -5.62 MeV 120 Sn(p,t) 118 Sn Q = -7.111 MeV Spectrometer at 7° Our recent work

11. Spectrometer at 7° 1 Wire Chamber : position of the light ejectile - triton energy Proton beam Target : 208 Pb & 120 Sn tritons 1 Paddle : dE/TOF – triton selection At 60 Me V Selection of B  window (5-7MeV)‏ thickness 6.4mm 2 Week-ends B p ( 208 Pb, 206 Pb) t & p ( 120 Sn, 118 Sn) t Our recent work

12. Gate on Tritons Without Gate triton deuteron 16 O(p,t)‏ 12 C(p,t)‏ 208 Pb(p,d) 207 Pb Ground State 5/2- 3/2- 13/2+ 7/2- Gate on Deuterons Exemple for 41MeV setting TOF E paddle1

13. 16 O(p,t)‏ 12 C(p,t)‏ No gate: gated on tritons: Deuterons acceptance ratio : Tritons acceptance ratio : Exemple for 41MeV setting TOF E paddle1

14. Excitation Spectrum of 206 Pb all fields overlapping

15. Excitation Spectrum of 206 Pb all fields superimposed Excited state of 206 Pb 14 O Ground state 10 C Ground state Excited state of 207 Pb So far no indication of bump or broad structure in the 206Pb spectrum

16. Excitation Spectrum of 120 Sn all fields overlapping

17. Excitation Spectrum of 120 Sn(p,t) : GPV? Deep hole states A hint for GPV in 120Sn: observation of cross-section enhancement (weak bump) at Ex=12MeV? The GPV? If yes, should increase at 0° Next Move : in SPRING 2009 120 Sn(p,t) 118 Sn & 208 Pb(p,t) 206 Pb proton beam @ 60 MeV K600 spectrometer @ 0° N=70

18. Futur plans and improvments? Thank you iThemba labs

20. Excitation Spectrum of 1118 Sn(p,t) : GPV? Deep hole states N=70 A hint for GPV in 120Sn: observation of cross-section enhancement (weak bump) at Ex=12MeV? The GPV? If yes, should increase at 0°

21. GPV could be searched for using Pair Transfer Reactions (t,p) reactions (p,t) reactions

22. At iThemba : 208 Pb(p,t) 206 Pb Q = -5.62 MeV 120 Sn(p,t) 118 Sn Q = -7.111 MeV GPV : L = 0 pairing mode Spectrometer at 0° Futur plans and improvments?