Toward understanding of the MIPP data V. Uzhinsky, 13 Sept. 2017 Content S. Banerjee report at 16 Aug. 2017 - questions MIPP experiment FTF calculations with exp. restrictions Description of NA49 and NA61/SHINE data Conclusion

S. Banerjee report at 16 Aug. 2017 - questions Validation of Hadronic Models using BNL E802 and MIPP data Data set from Fermilab E907: (T.S. Nigmanov et al., Phys. Rev. D83, 012002) FTFP model predictions show a spike at the highest energy which is more prominent in the most recent Geant4 version Source of the spike and underestimation of Xs? 2

S. Banerjee report at 16 Aug. 2017 - questions Some notes. Sunanda: p+H -> n+X at 56.8 GeV/c ! Data are at 58 GeV/c! FIG. 16. Measured cross sections from this experiment compared with neutron spectra generated by the DPMJET/FLUKA and LAQGSM Monte Carlos. Data and Monte Carlos are not corrected for geometric acceptance. The error bars are statistical only. 3

2. MIPP experiment Neutrons were identified and their energies measured through their interactions in the electromagnetic shower detector and hadron calorimeter. Immediately following the target was a 0.32 cm thick, 7.6 cm X 5.1 cm scintillation counter (SCINT) which was used to form the interaction trigger. There was a hardware requirement that the SCINT trigger fired, indicating an interaction in the target that produced ionization equivalent to 3 or more charged particles. This removed most of the events with fewer than three forward-going charged particles. 4

2. MIPP experiment In order to eliminate remaining uninteracted beam particles, the event was rejected if any charged track projected into the calorimeter’s fiducial area and had momentum >0.7 Pbeam. The final measured neutron energy then is Eemcal+Ehcal –Sum Etrk.cal, where Ehcal and Eemcal are the energies deposited in the HCAL and EMCAL, and Sum Etrk.cal is the summed energy of all charged tracks heading into the HCAL. 5

2. MIPP experiment There is reasonable agreement at xF > 0.6, but for lower xF the NA49 data at 158 GeV/c are lower than both our 58 and 84 GeV/c data by a factor 2. This discrepancy is not understood. 6

3. FTF calculations with exp. restrictions Corrected exp. data on P+P are used! Spectra of direct neutrons have small peaks at Xf ~ 0.95. They are connected with the reactions P+P->N + Δ++ (black curves). Decays of Λ and Σ are not very important (red lines). Introduction of Pch<0.7 Pbeam and Nch>=3 erases the peaks (blue lines). Normalisation of the calculations is very important. (dashed lines). It would be well to implement a good estimation of „neutron energy“. 7

3. FTF calculations with exp. restrictions Corrected exp. data on P+C are used! Spectra of direct neutrons have peaks at Xf ~ 0.95. They are connected with the reactions P+N->N + P. Decays of Λ and Σ are not very important. Introduction of Pch<0.7 Pbeam and Nch>=3 erases the peaks (blue lines). Normalisation of the calculations is very important. (dashed lines). It would be well to implement a good estimation of „neutron energy“. There is a real problem with P+C at 58 GeV/c! 8

3. FTF calculations with exp. restrictions Corrected exp. data on P+Bi are used! p+H, C, Bi data at 120 GeV/c can be described quite well. There is a problem with description at low energies or a problem in understanding the data. 9

4. Description of NA49 and NA61/SHINE data Neutron production in pp interactions at 158 GeV/c in the new FTF version is quite acceptable. 10

4. Description of NA49 and NA61/SHINE data Particle production in pp interactions at 20 - 158 GeV/c in the new FTF version is quite acceptable. 11

4. Description of NA49 and NA61/SHINE data NA61/SHINE data on p+C interactions at 31 GeV/c Preliminary data are presented in the validation suite. They are quite different from the final data. There is not a big difference between ref-tag 06 and last tag (June2017). 12

4. Description of NA49 and NA61/SHINE data Neutron production in p+Be, Pb at 12 – 19 GeV/c in the new FTF version is as it was in G4.3.ref06. 13

4. Description of NA49 and NA61/SHINE data Proton production in p+A at 120 GeV/c in the new FTF version is as it was in G4.3.ref06. 14

Conclusion It is complicated to understand and to reproduce experimental conditions of the MIPP experiment. Corrections of the data are problematic from my point of view. Data at 120 GeV/c can be described at abnormal assumptions. There is not a big discrepancy between FTF model in various ref-tags, according to our validation. Remember that small angle HARP experimental data are now described quite well in Bertini and FTF models. There are no arguments to ignore last FTF version. It would be well to re-think the MIPP data, but there is more actual task – understanding of NA49 and NA61/SHINE data on p+C interactions.