1. NUCLEAR FRAGMENTATION STUDIES WITH ANTIPROTON-NUCLEUS ANNIHILATIONS J. Kawada on behalf of the AE g IS collaboration. Albert Einstein Center for Fundamental Physics, Laboratory for High Energy Physics, University of Bern Contact e-mail: jiro.kawada@lhep.unibe.ch A nuclear emulsion film is photographic film with extremely high spatial resolution (better than 1  m), and sensitive to MIP particles. In recent experiments, large area nuclear emulsions were used thanks to the developments of automated scanning systems(Fig.2). Emulsion film & techniques Fig. 1. Left: AgBr crystals in emulsion layers observed by SEM. Right: A minimum ionizing track (MIP) from a 10 GeV/c pion  1  m Reference -C. Amsler et al., ‘A new application of emulsions to measure the gravitational force on antihydrogen’., JINST 8:P02015, 2013. -M. Kimura et al. (AEgIS collaboration), ‘Development of nuclear emulsions with 1 um spatial resolution for the AEgIS experiment’, Nucl. Inst. and Meth. A. (in press). - C. Amsler et al.,(AEgIS collaboration), ‘ Prospects for measuring the gravitational free-fall of antihydrogen with emulsion detectors ’, JINST 8:P08013, 2013. Bare emulsion SUS 20  m Vacuum flange The goal of the AE g IS experiment (CERN AD6) is to test the Weak Equivalence Principle (WEP) using antihydrogen. The gravitational sag of a beam will be measured with a precision of 1% on  g/g by means of a moiré deflectometer and a position sensitive annihilation detector made of emulsion films. The required position resolution should be ~2  m to achieve the 1% goal. The AE g IS experiment Fig.4 Left: Schematic view of the AE g IS apparatus Right:  g/g vs. number of reconstructed annihilations 16 layers 3D track reconstruction Fig. 2. Left: Emulsion scanning lab at LHEP, Bern University. Right: Schematic view of 3D track reconstruction Nuclear fragment studies in p annihilation with emulsion films Nuclear fragmentation characteristics on p annihilation is not well known in spite of its importance in many fields, nuclear physics, radiotherapy, and cosmology. -Production Multiplicity -Energy deposit around the annihilation vertex(an issue of radiotherapy) -Dependency on various nucleon -Hyper-fragment production study Abstract This work aims at collecting experimental data on low energy antiproton-nucleus annihilation, especially on nuclear fragmentation, by using emulsion films. In spite of their importance in many fields such as nuclear physics, astronomy and radiology, the characteristics ( e.g.hadronization and fragmentation multiplicities) of the stopping antiprotons annihilating on nuclei are not well known. For our study we exposed several thin targets (Al, Si, Ti, Cu, Ag, Au and Pb) to a very low energy antiproton beam from the CERN Antiproton Decelerator, delivering antiprotons to the AEgIS experiment (AD6). R&D on emulsion detector at LHEP Analysis results Nuclear Fragment Antiproton annihilation In emulsion film - Highly sensitive new emulsion gel A new emulsion gel and its applications are currently under R&D in Nagoya/Japan and LHEP/Bern. The new gel has a higher sensitivity and lower background density compared to the OPERA type emulsion(Fig.8, Tab.1). - Next generation scanning system with GPU Graphics Processing Unit with higher speed and flexible tracking. The latest GPU(GeForce Titan) has been installed into the current scanning system, and software development is going on. - Other emulsion applications New emulsion techniques will be used in many applications.  AEgIS experiment  Medical Application(precise beam monitor)  Muon radiography (A) (B) 50  m Fig.8. A 10 GeV/c pion track in (A) OPERA type (B) new emulsion. Tab.1. Comparison between OPERA-type and the new emulsions(made by Nagoya univ.). Emulsion layer (44micron) p Fig.5 Annihilation vertex detection in aluminum foil 260microns 150keV Fig.7 Multiplicity of MIPs(mainly charged pion) and heavily Ionizing particles(mainly protons) from p annihilation. Data points show the measured multiplicity for aluminum, silver, lead and gold and histograms show MC simulation based on the CHIPS model. The multiplicity of MIPs is in agreement with CHIPS model simulation. On the other hand, the multiplicity of heavily ionizing particle is in disagreement with CHIPS model for heavier nucleus than silver. In each material, 1k vertices have been reconstructed. An analysis is going on for each vertices to collect data on p annihilation features. MC(CHIPS) Data MC(CHIPS) Data MC(CHIPS) Data MC(CHIPS) Data SilverAluminum LeadGold Multiplicity of minimum ionizing particles(MIPs) Multiplicity of heavily Ionizing particles MC(CHIPS) Data MC(CHIPS) Data MC(CHIPS) Data MC(CHIPS) Data SilverAluminum LeadGold Gate valve Janusz chamber (10 -5 mbar) 5 T / 1 T magnet Flange Emulsion 5 films UHV/OVC separation (2  m titanium) Turbo pump Gate valve Antiproton exposure on metal foils with emulsion films Metal foils AlAl Cu Ti Si 6μm 20μm 5μm 400μm AgAg Pb Au Si 5μm 400μm Sample1 Sample2 Fig.3 Left: Schematic view of the Antiproton exposure Right: Schematic view of target metal foils on emulsion films Emulsion films were exposed to low energy antiprotons at the CERN- AD beam line, the site of the AEgIS experiment. Seven foils of pure materials were mounted in front of the emulsion film(Fig.3 right). - Antiproton average kinetic energy:150keV - Beam density : 10-20 antiprotons / mm 2  1-2 k annihilations/foil 68mm