Z. Phys. A 357, 107–111 (1997) ZEITSCHRIFT F ¨ UR PHYSIK A c  Springer-Verlag 1997 Angular dependence of proton inclusive spectra from dp → pX reaction at 3.34 GeV/c Dubna-Koˇ sice-Moscow-Tbilisi-Warsaw Collaboration V.V. Glagolev 1 , R.M. Lebedev 1 , G.D. Pestova 1 , S.S. Shimanskiy 1 , G. Martinsk´ a 2 , J. Urb´ an 2 , J. Hlav´ aˇ cov´ a 3 B. Pastirˇ c´ ak 4 , K.U. Khairetdinov 5 , A.K. Kacharava 6 , M.S. Nioradze 6 , T. Siemiarczuk 7 1 Joint Institute for Nuclear Research, Dubna, Russia 2 University of P.J. ˇ Saf´ arik, Koˇ sice, Slovak Republic 3 Technical University, Koˇ sice, Slovak Republic 4 Institute of Experimental Physics, Slovak Academy of Sciences, Koˇ sice, Slovak Republic 5 Lebedev Institute of Academy of Sciences, Moscow, Russia 6 High Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia 7 Institute for Nuclear Research, Warsaw, Poland Received: 14 February 1996 / Revised version: 2 September 1996 Communicated by Th. Walcher Abstract. Inclusive differential cross sections for the dp → pX reaction at 3.34 GeV/c are presented for different pro- ton production angles in the deuteron frame. At large an- gles some irregularities have been observed in the spectra. The obtained angular dependence of the inclusive differential spectra for the backward hemisphere allows a detailed com- parison with models describing dp interactions. This com- parison shows the importance to consider the contributions from rescattering processes at production angles around 90 ◦ . Conclusion is made about the necessity to involve additional mechanisms into existing models in order to describe the an- gular dependence of the inclusive proton cross sections. PACS: 25.10.+s; 24.45.-z 1 Introduction Apart from the deuteron being the simplest nuclear sys- tem, questions still remain about its structure at internu- cleon distances below 1 fm (internal nucleon momenta above 0.2 GeV/c), where the nucleon overlap begins and there- fore one can expect some manifestation of the nucleon quark structure and non-nucleon degrees of freedom in the deuteron wave function. Information on the deuteron wave function can be ex- tracted from ed, γd and hd processes, once the basic re- action mechanisms and the characteristics of the elemen- tary processes on nucleons have been selected. The use of hadron beams has, partially, the advantage of significantly greater cross sections. Manifestations of non-nucleon and quark degrees of freedom in the deuteron can be searched for namely in the region forbidden for the processes on free nucleons (i.e. in the cumulative kinematical region). The nu- cleon spectra at angles larger then 90 ◦ , in the deuteron frame, and momenta greater than 0.2 GeV/c can give information about this region. The present work is a continuation of the deuteron struc- ture and interaction mechanisms study with the 1 m hydro- gen bubble chamber [1]. Bubble chambers enable an exclu- sive approach to different reactions and in particular to the dp → ppn channel. Its cross section is σ = (37.2 ± 1.4) mb at 3.34 GeV/c [2] and its characteristic features have been studied in [1]. Here for the first time attention was called to the importance of non-pole contributions in processes in- volving nucleons produced into the backward hemisphere. The experimental results discussed in [1] and [3–7] stim- ulated the development of theoretical models [8–11], de- scribing the deuteron structure at small distances in differ- ent ways and considering different interaction mechanisms. The lack of data on the angular dependence of the inclusive spectra has not allowed to make unambiguous conclusions about the reaction mechanisms and to seperate them. In this work first data on the angular dependence of in- clusive proton spectra at 3.34 GeV/c from the dp → pX reaction are presented and compared with results of differ- ent models [9–11] for the proton inclusive spectra at large angles which is the most favourable region for observing non-nucleonic degrees of freedom [12]. 2 Experiment and comparison with models Experimental data have been obtained with the 1 m bubble chamber of the LHE JINR at Dubna. The chamber was ex- posed to beams of vector polarized [13] and also unpolarized deuterons at 3.34 GeV/c momenta. The data analysed in [1] have been taken at the same energy, so the analysis could be carried out on the combined statistics. Compared to the sam-