1. SCIENCE GOALS AND OBJECTIVES: THEORETICAL STUDIES OF MAGNETIC RECONNECTION HAVE RECENTLY CONCLUDED THAT IT MUST BE LOCALIZED TO SMALL SPATIAL SCALES IN ORDER TO PROCEED AT RATES OBSERVED IN SOLAR FLARES. EVIDENCE OF THESE SMALL SCALES HAS NOT BEEN FOUND IN DIRECT CORONAL OBSERVATIONS PRINCIPALLY DUE TO THE SMALL EMISSION MEASURES OF EXPECTED STRUCTURES. THE ENERGY RELEASED BY CORONAL RECONNECTION PRECIPITATES INTO COOLER DENSER LAYERS WHERE SMALL SCALES CAN BE OBSERVED FAR MORE READILY. UPFLOWS (CHROMOSPHERIC EVAPORATION) AND DOWNFLOWS (CHROMOSPHERIC CONDENSATION) IN FLARE RIBBONS MAY THEREFORE BE THE BEST PLACE TO FIND EVIDENCE OF AND STUDY THE STRUCTURE OF CORONAL RECONNECTION OCCURRING IN SOLAR FLARES. IN A WELL-REGARDED THEORETICAL INVESTIGATION FISHER (1986) IDENTIFIED THE CONDITION FOR THE INITIATION OF SIGNIFICANT DOWNFLOWS (CHROMOSPHERIC CONDENSATION ACCOMPANYING EXPLOSIVE EVAPORATION) AND THEIR EXPECTED VELOCITIES. HE ALSO PREDICTED THAT THE DOWNFLOW IN A SINGLE ENERGIZED FLUX TUBE WOULD PERSIST ONLY AS LONG AS A SOUND PULSE TAKES TO TRANSIT THE CHROMOSPHERIC SCALE HEIGHT: ROUGHLY TEN SECONDS. ONLY WITH THE SUPERIOR SPATIAL RESOLUTION OF THE IRIS SPECTROGRAPH COUPLED WITH ITS HIGH TIME CADENCE HAVE OBSERVATIONS FINALLY REVEALED CONDENSATION FLOWS DECAYING OVER SUCH SHORT TIMES. GRAHAM AND CAUZZI (2015) MEASURED DOWNFLOW VELOCITIES USING BISECTORS OF MG II LINES IN A FLARE RIBBON AND FOUND THEY DROPPED BY HALF FROM 25 KM/S IN ABOUT 20 SECONDS. PREVIOUS STUDIES HAD OBSERVED FAR LONGER DECAY TIMES 2-3 MINUTES PROBABLY BECAUSE THEY HAD FAILED TO RESOLVE ELEMENTARY ENERGIZED LOOPS INDIVIDUALLY AS IRIS FINALLY HAS. THE GOAL OF THIS PROJECT IS TO STUDY TRANSIENT FLARE DOWNFLOWS OBSERVED BY IRIS AT HIGH SPATIAL AND TEMPORAL RESOLUTION IN ORDER TO UNDERSTAND THE RECONNECTION PROCESS. 2. MISSION DATA TO BE USED: PRIMARY DATA: IRIS: EXISTING HIGH CADENCE (<11S) SIT-AND-STARE OBSERVATIONS WITH FLARE RIBBON CROSSING THE SLIT. (AT LEAST 10 SUITABLE DATA SETS HAVE BEEN IDENTIFIED). SECONDARY DATA: SDO/HMI: PRE-FLARE LINE-OF-SIGHT MAGNETOGRAMS FOR MAGNETIC CONTEXT. SDO/AIA: EUV IMAGES TO IDENTIFY FLARING LOOPS TO PROVIDE THEIR LENGTHS. RHESSI: IF AVAILABLE TO DEFINE ELECTRON BEAM PROPERTIES. 3. DATA ANALYSIS METHODOLOGY AND MODELS: SIT-AND-STARE IRIS OBSERVATIONS FROM THE OPTICALLY THIN SI IV LINE WILL BE USED TO TO STUDY TRANSIENT DOWNFLOWS IN THE RIBBONS OF SEVERAL FLARES. THE TIME HISTORY OF THE DOWNFLOW VELOCITY AT EACH SLIT PIXEL WILL BE FOUND FROM SPECTRA. AN OPTICALLY THIN LINE PROVIDES THE VELOCITY MORE DIRECTLY THAN THE OPTICALLY THICK MG II LINE USED IN PAST WORK. IN DATA SETS WHICH INCLUDE BOTH 1394 AND 1403 LINES THE ASSUMPTION OF OPTICAL THINNESS MAY BE VERIFIED. WE WILL INTERPRET DATA USING A ONE-DIMENSIONAL MODEL ENERGIZED BY MAGNETIC RECONNECTION (PREFT) PREVIOUSLY USED TO SYNTHESIZE CORONAL AND TR EMISSION FROM FLARES. IT WILL BE RUN IN MODES WITH PURELY THERMAL (I.E. CONDUCTIVE) ENERGY TRANSPORT AS WELL AS MODES WITH A POPULATION OF NON-THERMAL ELECTRONS. FOLLOWING PRIOR METHODOLOGY LOOP LENGTHS AND MAGNETIC FIELD STRENGTHS WILL BE CONSTRAINED USING OBSERVATIONS FROM SDO/AIA AND SDO/HMI RESPECTIVELY. PARAMETERS OF ANY ELECTRON BEAM WILL BE CONSTRAINED USING DATA FROM RHESSI WHEN AVAILABLE. 4. RELEVANCE OF THE PROBLEM: THE RESEARCH AIMS TO BETTER UNDERSTAND THE RECONNECTION PROCESS OCCURRING DURING A SOLAR FLARE. THIS AIM ADDRESSES 1 MISSION GOAL OF IRIS AND 2 GOALS FROM THE MOST RECENT HELIOPHYSICS DECADAL SURVEY (DS) IRIS GOAL: 1. WHICH TYPES OF NON-THERMAL ENERGY DOMINATE IN THE CHROMOSPHERE AND BEYOND. DS GOALS: 1. DETERMINE THE ORIGINS OF THE SUN S ACTIVITY AND PREDICT THE VARIATIONS IN THE SPACE ENVIRONMENT 4. DISCOVER AND CHARACTERIZE FUNDAMENTAL PROCESSES THAT OCCUR BOTH WITHIN THE HELIOSPHERE AND THROUGHOUT THE UNIVERSE.