1. 05/03/20161 Cumulative proton production in Cumulative proton production in nuclei-nuclei collisions Elena Litvinenko Anatoly Litvinenko litvin@moonhe.jinr.ru VBLHEP, JINR, DUBNA

2. 05/03/20162 Outline.  Introduction  Cumulative particles: a few word about  Why they can be interesting for nuclei-nuclei collisions?  A few estimations  Conclusions

3. 05/03/20163 Cumulative particles - definition 1. Subthreshold 2a. Target fragmentation region 2b. Beam fragmentation region

4. 05/03/20164 L.S.Schreder et al.,. Phys.Rev.Lett., 43(24), 1787, (1979). A.M.Baldin, Yad. Fiz.(Rus),v 20, 1201, (1979). Independence spectra shape from initial energy

5. 05/03/20165 Protons. Cumulative and evaporated R.Ammar et al, Pisma v JETF (Rus), V.49(4),189, 1989 R.Ammar et al, Preprint FIAN (Rus), 48(4),1989 evaporated cumulative

6. 05/03/20166 Independence spectra shape from atomic mass number O.P.Gavrishchuk et al., Nuclear Physics, A(523), 589, (1991).

7. 05/03/20167 Some specifics of cumulative particle production Independence spectra from initial energy Clear separation between evaporated and cumulatve nucleons Spectra shape independence from atomic mass number Spectra shape independence from beam particle (hadrons, leptons, light nuclei) Deuteron fragmetation into cumulatve particle

8. 05/03/20168 Hot FLUCTON Models of cumulative particle production Cold FLUCTON C C NOYES A.V.Efremov, PEPAN. V13(3), 613, 1982 D.I.Blokhintsev, JETF (Rus.) V.33,1295, (1957)

9. 05/03/20169 Models with Cold FLUCTON : High momentum component in target nucleus (different nature for different models) Cumulative proton

10. 05/03/201610 Models with Cold FLUCTON Flucton(s) is in the initial state of the colliding nuclei Cumulative particles are produced at the initial stage of collision Can we use cumulative particles to obtain information about the initial stage of the collision? Can they be used as the probe for the density of the exited hadronic matter?

11. 05/03/201611 In heavy ion collisions more exited (hot and dense) hadronic matter should appear at the initial stage of collision. The probes, which give information about the property this hadronic matter, have to be connected with this stage. But at low energy (say ) such probes are difficult (or impossible) for the use. For example:  the cross section for the jet production is extremely small for low energy  the spectra of direct photon production have big admixture from the resonances decay at low photon momentum and small value of cross section for high momentum.. It means, that it is especially important to find the probes which are connected to the initial state of collision at the small initial energies.

12. 05/03/201612 Why it can be interesting in nuclei-nuclei collisions? The possible mark for the initial state of the target nucleus Cumulative protons spectra can not be explained as thermal spectra of the protons emitted from the fireball with the reasonable temperature. So, if you detect the proton with the momentum 0.3 GeV/c or more in the backward semi sphere, you can conclude that you have collision with the flucton in the initial state of target nucleus.

13. 05/03/201613 Thermal and cumulative spectra RHIC condition for fireball Blue line – cumulative protons Red line – protons from fireball

14. 05/03/201614 Why it can be interesting in nuclei-nuclei collisions? 1.Backward protons are produced during the first stage of collision 2. Spectrum have to be sensitive to the density of the compressed fireball. Analogy with high P T hadrons production at RHIC. Jet Quenching.

15. 05/03/201615 The model for spectra shape modification (two stage) 1. Fireball formation 2. Passing cumulative particle through fireball 1. Fireball formation Nuclei without diffuse layer Target nucleon is frozen during collision No formation length The cross section approximation is taken from: V.S.Barashenkov and N.V.Slavin, PEPAN, V.15(5),p.997,(1984) 2. Passing cumulative particle through fireball Uniform distribution of fluctons over target volume Particle in fireball (i.e. particle with momentum less than 0.5 GeV/c) is frozen Cross section is taken the same as for fireball formation

16. 05/03/201616 Spectra shape modification (angular dependence) b = 0 fm b = 7 fm pA(blue) AuAu(red)

17. 05/03/201617 Spectra shape modification (angular dependence) b = 0 fm b = 7 fm pA(blue) AuAu(red)

18. 05/03/201618 Spectra shape modification (momentum dependence) b = 0 fmb = 7 fm pA(blue) AuAu(red)

19. 05/03/201619 Spectra shape modification (momentum dependence) b = 7 fm b = 0 fm pA(blue) AuAu(red)

20. 05/03/201620 The possible set up for fix. targ. 1 m (ToF) Scintillation counters Hadron spectrometer without a magnet 20 cm0.5 cm

21. 05/03/201621 target beam Wall of hadron spectrometers without a magnet

22. 05/03/201622 Conclusion. It seems that cumulative particle can give interesting information about space-time structure of nuclear- collision. The numbers of detected deuterons are expected to be three times smaller that numbers of protons.

23. 05/03/201623 Backup slides

24. 05/03/201624 Have we observables for estimation hadronic matters properties at the first stage for not so big initial energy? High Energy - Bjorken equation But it have to be ifif Under suggestion

25. 05/03/201625 Historically energy density was estimated using final Energy density and Bjorken equation for

26. 05/03/201626 Some experimental features of backward proton production in nucleon-nuclei collisions : 1.The spectra show a weak beam energy dependence starting from momentum 4 CeV/c. 2.The spectrum shape is independent from target mass number 3.There is also a weak spectrum shape dependence from the type of beam particle (for the lepton, proton and lights nuclei (A < 12)). 4.The cross section has a strong atomic mass dependence ~ A n, n>1. - V.Lukyanov, A.Titov, Part. And Nucl., V.10(4), p.815 (1979) - A.Baldin, Part. And Nucl., V.8(3), p.429 (1977) - A.Efremov, Part. And Nucl., V.13(5), p.613 (1982) - L.Frankfurt and M.Strikman, Phys.Rep.,V.76,p.215,(1981) - V.Stavinsky, Part. And Nucl., V.10(5), p.979 (1979)

27. 05/03/201627 The possible set up. 1 m (ToF) E Scintillation counters Hadron spectrometer without a magnet

28. 05/03/201628

29. 05/03/201629 First data from the first RHIC RUN Jet Quenching

30. 05/03/201630 Jet tomography 20-60% STAR Preliminry 20-60% Back-to-back suppression depends on the reaction plane orientation In-plane Out-plane energy loss dependence on the path length!