OBJECTIVES:IN SEPTEMBER 2016 NASA WILL LAUNCH A ROCKET TO SEND THE OSIRIS-REX SPACECRAFT ON A RENDEZ VOUS MISSION TO B-TYPE ASTEROID 101955 BENNU FOR SAMPLING ITS SURFACE. MUCH OF THE DISCUSSION ON THESE ROCKS WILL UNDOUBTEDLY INVOLVE UNDERSTANDING THEIR IRRADIATION HISTORY.FOR HOW LONG WERE THE ROCKS EXPOSED TO GALACTIC COSMIC RAYS? AT WHAT DEPTH WERE THE ROCKS BURIED WHEN THEY WERE EXPOSED TO THOSE COSMIC RAYS? DID SUCH IRRADIATION AFFECT THE CHEMICAL AND ISOTOPIC COMPOSITIONS OF THE ROCKS AND IF YES CAN SUCH EFFECTS BE CORRECTED FOR? HOW ARE COSMOGENIC EFFECTS AFFECTED BY THE TARGET COMPOSITION AND ITS WATER CONTENT? THE BEST TRACERS OF THOSE EFFECTS ARE ISOTOPES WITH LARGE CAPTURE CROSS SECTIONS AND RESONANCE INTEGRALS FOR THERMAL AND EPITHERMAL NEUTRONS. LANTHANIDES (REES) POSSESS MANY ISOTOPES WITH LARGE THERMAL NEUTRON CROSS SECTIONS AND RESONANCE INTEGRALS. THEY HAVE PROVEN TO BE EXTREMELY USEFUL FOR UNDERSTANDING THE COSMIC RAY EXPOSURE HISTORY OF LUNAR ROCKS AND METEORITES. GIVEN THAT OSIRIS-REX WILL RECOVER SURFACE ASTEROIDAL SAMPLES CONSIDERATION OF THOSE EFFECTS WILL BE IMPORTANT.THERE IS LITTLE EXPERTISE IN THE USA ON CALCULATION OF NEUTRON CAPTURE EFFECTS IN REES AND MUCH OF THE FOCUS IN REE ISOTOPE MEASUREMENTS HAS BEEN IN THE ANALYSIS OF SM AND ND FOR GEOCHRONOLOGIC APPLICATIONS. THE PROPOSED WORK WILL ALLOW US TO (1) CONTINUE DEVELOPING AND TESTING CHROBOT A NEW AUTOMATED CHROMATOGRAPHY SYSTEM FOR PURIFYING REES TO MEASURE NEUTRON CAPTURE EFFECTS (2) DOCUMENT COSMOGENIC EFFECTS FOR REES IN TARGETS OF CARBONACEOUS CHONDRITE COMPOSITIONS FOR WHICH ALMOST NO DATA IS AVAILABLE AND (3) DEVELOP THE SCIENTIFIC CONTEXT FOR INTERPRETING THOSE VARIATIONS BY RUNNING SIMULATIONS OF NEUTRON CAPTURE EFFECTS IN TARGET COMPOSITIONS REPRESENTATIVE OF THE MATERIALS THAT OSIRIS-REX MAY ENCOUNTER.METHODOLOGY:OVER THE PAST 2 YEARS WE HAVE DEVELOPED AN ALL-TEFLON PNEUMATIC CHROMATOGRAPHY SYSTEM TO SEPARATE REES FROM ONE ANOTHER. THE MOTIVATIONS FOR DEVELOPING THIS SYSTEM ARE TWO-FOLD: (1) IT ALLOWS US TO ISOLATE ELEMENTS THAT ARE NOTORIOUSLY DIFFICULT TO SEPARATE FROM ONE ANOTHER BY RUNNING LONGER COLUMNS UNDER CONTROLLED TEMPERATURE CONDITIONS YIELDING BETTER CHROMATOGRAPHIC SEPARATIONS AND (2) IT ALLOWS US TO ACHIEVE BETTER SEPARATIONS IN A COMPUTER CONTROLLED PROCEDURE USING LESS COLUMN PASSES THUS MINIMIZING THE RISK OF SAMPLE LOSS CONTAMINATION AND MISHANDLING. MORE ELEMENTS CAN BE SEPARATED IN A SINGLE COLUMN PASS MAKING OPTIMUM USE OF THE SAMPLES.THE SYSTEM IS ESTABLISHED AND THE NEXT 3 YEARS WILL BE DEVOTED TO ASSESSING ITS ROUTINE OPERATION TO SEPARATE REES FOR STUDY OF NEUTRONCAPTURE EFFECTS. SCIENTIFICALLY WE WILL ADDRESS THE QUESTION OF HOW DO DIFFERENT TARGET MATERIALS AND SECONDARY ENERGY SPECTRA AFFECT THE ISOTOPIC COMPOSITIONS OF THE REES? THIS WILL BE INVESTIGATED BY (1) COMBINING ISOTOPIC ANALYSES OF ELEMENTS THAT HAVE DIFFERENT SENSITIVITIES TO DIFFERENT NEUTRON ENERGIES AND (2) STUDYING THOSE EFFECTS IN CARBONACEOUS CHONDRITES TAKEN AS PROXIES FOR BENNU SAMPLES. THOSE MEASUREMENTS WILL BE COMBINED WITH ONGOING SIMULATIONS OF NEUTRON CAPTURE EFFECTS IN AN INVERSION CALCULATION TO DERIVE THE SECONDARY NEUTRON ENERGY SPECTRUM. THE CALCULATIONS WILL INVESTIGATE HOW TARGET COMPOSITIONS (E.G. VARIABLE WATER CONTENTS) AFFECT COSMOGENIC EFFECTS FOR THE REES.RELEVANCE:THIS STUDY WILL STRENGTHEN THE EXPERTISE OF A US LAB IN THE MEASUREMENTS AND INTERPRETATION OF COSMOGENIC NEUTRON CAPTURE EFFECTS IN PLANETARY SURFACES OF CARBONACEOUS CHONDRITE COMPOSITIONS A KEY ASPECT OF THE STUDY OF THE OSIRIS-REX MISSION. IT IS THUS HIGHLY RELEVANT TO NASA'S STRATEGIC OBJECTIVES (SOLICITATION NNH16ZDA001N-LARS) WHICH INCLUDE "DEVELOPMENT OF LABORATORY INSTRUMENTATION AND/OR ADVANCED TECHNIQUES REQUIRED FOR THE ANALYSIS OF RETURNED SAMPLES" (DOCUMENT C18 OF THE SOLICITATION PAGE C.18-1).