OBJECTIVES: POWER-LAW SPECTRUM IS THE MOST COMMON SPECTRUM OF ENERGETIC PARTICLES. HOWEVER WE OFTEN SEE THAT SOLAR ENERGETIC PARTICLES EXHIBIT POWER-LAW SPECTRA WITH TWO OR SOMETIMES MORE DIFFERENT SPECTRAL SLOPES IN DIFFERENT ENERGY BANDS. THOSE WITH TWO DIFFERENT POWER-LAW SLOPES ARE CALLED DOUBLE POWER-LAW SPECTRUM. RECENTLY THE OBSERVATION ATTRACTS A GREAT DEAL OF INTEREST IN THE HELIOSPHERIC PHYSICS COMMUNITY. WHILE THE SINGLE POWER-LAW SPECTRUM HAS A STRONG THEORETICAL FOUNDATION THERE IS NO CLEAR EXPLANATION FOR THE DOUBLE POWER-LAW SPECTRUM. SOME PUBLICATIONS ATTRIBUTE IT TO A MECHANISM OF PARTICLE ACCELERATION IN A SHOCK ENVIRONMENT BUT A FEW OTHERS SUGGEST IT IS DUE TO PARTICLE PROPAGATION FROM A REMOTE SOURCE IN THE CORONA TO 1 AU. THE GOAL OF THIS PROPOSED RESEARCH IS TO IDENTIFY WHAT MECHANISMS AND CONDITIONS PRODUCE THE DOUBLE POWER-LAW SPECTRUM OBSERVED BY SPACECRAFT IN INTERPLANETARY SPACE. THE RESULT WILL LEAD TO A BETTER UNDERSTANDING OF THE PHYSICS OF PARTICLE ACCELERATION AND TRANSPORT IN THE CORONAL AND HELIOSPHERIC MAGNETIC FIELDS WHICH IS CRUCIAL TO DEVELOPING TOOLS FOR SPACE WEATHER FORECAST AND RADIATION HAZARD MITIGATION. DATA SOURCE AND METHODOLOGY: OUR PROPOSED WORK BUILDS ON MEASUREMENTS MADE BY NASA MISSIONS I.E. ACE STEREO WIND ULYSSES IMP-8 AND HELIOS. WE USE ALL ENERGETIC PARTICLE MEASUREMENTS ON THESE MISSIONS (ULEIS SIS LET SIT HISCALE COSPIN AND SO ON). TO AID OUR ANALYSIS AND INTERPRETATION WE ALSO USE PLASMA AND MAGNETIC FIELD DATA. ENERGETIC PARTICLE FLUX MEASUREMENTS BY THESE MISSIONS WILL BE BUILT INTO ENERGY SPECTRA USING VARIOUS SCHEMES. A LARGE NUMBER OF EVENTS WITH A DOUBLE POWER-LAW EVENTINTEGRATED SPECTRUM WILL BE SELECTED. WE WILL ANALYZE THE DETAILED PROPERTIES OF SOLAR ENERGETIC PARTICLES INCLUDING THEIR SPECTRUM SLOPES AND BREAK ENERGY. IN THIS NEW ANALYSIS WE WILL DISSECT SEP EVENTS INTO DIFFERENT PHASES: RISING PEAK AND DECAY (RESERVOIR) TO STUDY HOW THE DOUBLE POWER-LAW SPECTRUM EVOLVES IN TIME. WE WILL SELECT EVENTS SIMULTANEOUSLY OBSERVED BY MULTIPLE SPACECRAFT LOCATED AT DIFFERENT LONGITUDES LATITUDES AND RADIAL DISTANCES. RADIAL DEPENDENCE WILL ALSO BE STUDIED STATISTICALLY USING SINGLE-SPACECRAFT MEASUREMENTS. IN THIS WAY PROPERTIES OF THE DOUBLE POWER-LAW SPECTRUM AND THEIR DEPENDENCE ON LOCATION MAGNETIC CONNECTIVITY PARTICLE SPECIES OTHER PARAMETERS ARE THOROUGHLY ANALYZED FOR THE PURPOSE OF DETERMINING THE FUNDAMENTAL PHYSICS PRODUCING THE PHENOMENON. COMPARISONS OF THE OBSERVATIONAL RESULTS WITH MODEL CALCULATIONS WILL FURTHER HELP US SOLIDIFY OUR CONCLUSION. RELEVANCE: THE SCIENTIFIC OBJECTIVE MATCHES THE GOALS OF HSO MISSIONS: DISCOVER THE MECHANISMS AND SITES OF ENERGETIC PARTICLE ACCELERATION IN THE LOW CORONA AND THE INTERPLANETARY MEDIUM AND THEIR SUBSEQUENT TRANSPORT IN HELIOSPHERIC MAGNETIC FIELDS ALL OF WHICH ARE PROCESSES FUNDAMENTAL TO THE HELIOSPHERIC PHYSICS. IT ADDRESSES TWO (1&4) OF THE FOUR HIGH-LEVEL SCIENCE GOALS FROM THE HELIOPHYSICS DECADAL SURVEY.