Neutron Production in THICK Targets Induced by High Energy Ions: Unexpected Effects and Perspectives Reinhard Brandt Kernchemie, Fachbereich Chemie, Philipps Universität, D Marburg and Fundraising-Initiative Kernchemie, Marburg ( 1.) Neutron experiments at the Synchrophasotron, JINR, Dubna, Russia 2.) Neutron experiment at the Bevalac, LBL, Berkeley, California 3.) Suggested neutron experiments, in order to design safe neutron shieldings and target systems for high intensity machines. [prepared for EU-Parlament in Brussels: „Nuclear Energy Workshop“, Nov ] Brussels.ppp.11.08www.fundraising-initiative.de

THE COLLABORATION PRODUCING THIS WORK: R. Brandt, V.A. Ditlov, K.K. Dwivedi, W. Ensinger,E. Ganssauge, Guo Shi-Lun, M. Haiduc, S.R. Hashemi-Nezhad, H.A. Khan, M.I. Krivopustov, R. Odoj, E.A. Pozharova, V.A. Smirnitzky, A.N. Sosnin, W. Westmeier, M. Zamani (Marburg - ITEP/Moscow – Washington –Beijing –Bucharest – Sydney - Dubna - Islamabad – Jülich – Thessaloniki) Interactions of relativistic heavy ions in THICK heavy element targets and some unresolved problems. Physics of Elementary Particles and Atomic Nuclei, 39(2), (2008), 507 [Original version, published by JINR, Dubna (Ru)] and Physics of Particles and Nuclei, 39(2), (2008), 259 – 285, and Studies with SSNTD and nuclear chemistry on nuclear reactions induced by relativistic heavy ions in THICK targets: a review “Proc. 23 rd International SSNTD Conf., Beijing, 2006”, in Radiation Measurements. 43, (2008),

Neutron counting results Tableau 1: Neutron emission from THICK Pb-targets. The total number of thermal neutrons n, generated by one primary ion( 1-H, 2-H, 4-He, or 12-C ) in a very thick lead target (Φ = 20 cm and L = 60 cm), moderated within 1 m 3 paraffin and measured by Vassilkov et al. in Dubna (1983) 3.7 : 1  (5.0  0.3): Such a result cannot be calculated. This constitutes an “unresolved problem”. IonMass AThermal neutrons n at E T /A=1 GeV Thermal neutrons n at E T /A=3.7 GeV n at (E T /A=3.7 GeV) n at (E T /A=1.0 GeV) H    0.2 H   33.4  0.2    93.9  0.2 C  5641   0.3

Tableau 2: Experimental setup, called GAMMA-2. Introduced in 1995, since 2007 an IAEA Benchmark target. This target allowed in Dubna two-parameter measurements: 1.) Nuclear destruction within Cu via radiochemistry 2.) neutron measurements with chemical & SSNTD sensors La-sensors U-sensors Chemical sensors Various SSNTD-sensors

Tableau 3 : Calculated total neutron numbers N for GAMMA-2 according to the DCM/CEM model. Comparison with experimental results for 44 GeV 12-C: The experiment in Dubna gave N=(700±140) neutrons, the model calculated 280 neutrons for the Pb-target. 12-C

Tableau 4: Neutron fluences at the Bevalac accerator LBL (Lawrence Berkeley Laboratory, USA) around a 20 cm THICK Cu target Irradiated with 72 GeV 40-Ar in the year Facts are: Secondary fragments destroy Cu nuclei stronger when they are produced by 72 GeV 40-Ar as compared to 44 GeV 12-C. This “unresolved problem” has been observed clearly with radiochemical methods. The neutron fluence during the above irradiation (72 GeV) was unexpectedly VERY LARGE, but the measured neutron fluence was never published. What has been “cooking” in Berkeley? Protocol from memory: LBL irradiation with 5*E8 ions/sec of 72 GeV 40 Ar + THICK Cu at from a.m. (44 min) B – Bevalac accelerator H –HILAC (Heavy Ion Accelerator) “ Synchrocyclotron (not working) 2 – Cafeteria 3 – Bldg 70: Nuclear Chemistry 4 – Bldg 50: Nuclear Physics 5 – Administration 6 – Exit downhill to the UC campus B H 100 m

Tableau 5: What happened close to the Bevalac in detail during the irradiation on March with 72 GeV 40-Ar (5*10 8 ions/sec) ? 8 16 a.m.: start irradiation 8 30 : neutron alarm on TOP of Bevalac (Monitor turned off) 8 40 : neutron alarm in the HILAC (Monitor turned off) : Ar-beam turned off The experimental hall & 10 4 to Fe Bevalac are well shielded with massive concrete in 4π geometry 72 GeV Ar-ion beam Target: 20 cm Cu block, 8 cm Ф Certain result: The accelerator concrete shielding was sufficient for decades of experiments with THIN targets. This shielding was utterly insufficient for THICK target experiments Cu

Tableau 6 : Summary, At present one can calculate the ratio for experimental to theoretical neutron fluence only with the following accuracy in the ion energy range of about 1 to 10 GeV (ADS: “Energy-plus-Transmutation”( E&T) [Krivopustov], JINR, Dubna, etc) only up to +(22 ± 14) %, Hashemi-Nezhad, NIMA, 501 (2008), about 10 to 100 GeV not-at-all, due to the “excess neutrons” observed in Dubna. In addition, one MAY have seen enhanced “complete nuclear destruction” into individual nucleons during the interaction of >200 GeV 238 U in THICK targets (next foil). This would increase the neutron production further.

Tableau 7 : The complete destruction of 220 GeV 238-U: “Interactions of relativistic 238-U and light targets”. H.A. Khan, et al. NIM (1991) B61, The FAT and round etch pits are due to U ions and FF: NOT of interest! THE TINY ETCH PITS are of INTEREST: “ Complete Nuclear DESTRUCTION ?? or “Particle therapy ??”

Tableau 8: Outlook We need to know experimental results about the neutron emission from THICK targets ( examples: Cu, Pb, nat U ) irradiated with ions having E(total) > 10 GeV. WHY ? To have proper radiation protection shielding for high energy and high intensity ion accelerators under construction To find out, how much “excess neutrons” (compared to standard model calculations) one observes experimentally for ions with energies E(total) > 10 GeV New technological applications are conceiveable. To find out, WHY we observe “excess neutrons”