A1309.01

Imaging ParametersImaging Parameters

A1309.01

Title:grid_parameters_color.figCreator:fig2dev Version 3.1 Patchlevel 1Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.

Imaging ParametersImaging Parameters

A1309.01

HESSIHESSI

A1309.02

HESSI Science ObjectiveHESSI Science Objective

Impulsive Energy Release in the Corona Acceleration of Electrons, Protons, and Ions Plasma Heating to Tens of Millions of degrees Energy and Particle Transport and Dissipation

To explore the basic physics ofparticle acceleration and

explosive energy release in Solar Flares

A1309.03

HESSI Non-Solar Science HESSI Non-Solar Science ObjectivesObjectives

The Crab Nebula– Imaging spectroscopy with 2” resolution

Gamma Ray Bursts and Cosmic Transient Sources– Detected over a large fraction of the sky– High resolution spectroscopy– Search for cyclotron line features

Steady X-ray and gamma-ray sources (point and diffuse)– Detect by Earth occultation or through the rear grids– Obtain high resolution spectra– Search for line features

A1309.04

HESSI Primary ObservationsHESSI Primary Observations

Hard X-ray Images– Angular resolution as fine as 2 arcseconds– Temporal resolution as fine as 10 ms– Energy resolution of <1 keV from 3 keV to

400 keV High Resolution X-ray and Gamma-ray Spectra

– keV energy resolution– To energies as high as 20 MeV

A1309.05

Complementary ObservationsComplementary Observations

SOHO EUV images and spectraCoronagraph imagesParticle spectra and abundances

GOES Images from the Soft X-ray ImagerACE Energetic particle spectra and

abundancesGround-based Observatories

Radio and optical images and spectra

Magnetograms

A1309.06

HESSI FirstsHESSI Firsts

Hard X-Ray Imaging Spectroscopy

High Resolution Spectroscopy of Solar Gamma-Ray Lines

Hard X-Ray and Gamma-Ray Imaging above 100 keV

Imaging of Narrow Gamma-Ray Lines

High Resolution X-ray and Gamma-Ray Spectra of Cosmic Sources

Hard X-Ray Images of the Crab Nebula with 2-arcsecond Resolution

A1309.07

Relevance to Strategic PlanRelevance to Strategic Plan

Part of the Solar Connections Program - in the Roadmap for the next solar maximum.

Seeks to understand fundamental physics of solar flare energy release and particle acceleration.

Relevant to understanding relation between flares and coronal mass ejections and their effects on the Earth and its environs.

A1309.08

Expected Numbers of FlaresExpected Numbers of FlaresMicroflares Tens of

thousands

Hard X-ray flares with crude imaging and spectra >1000to >100 keV

Hard X-ray flares with >103 counts s-1 detector -1 Hundredsabove 20 keV allowing spatial scales to befollowed on timescales of 0. I s

Flares sufficiently intense to allow the finest Tenspossible imaging spectroscopy

Flares with the detection of gamma-ray lines Up to 100

Flares with detailed gamma-ray line spectroscopy Tensand the location and extent of the sourcedetermined to ~40 arcseconds

A1309.09

HESSI Observational HESSI Observational CharacteristicsCharacteristics

Energy Range 3 keV to 20 MeV Energy Resolution ~1 keV from 3 keV to 1 MeV

Increasing to 5 keV at 20 MeV Angular Resolution 2 arcseconds to 40 keV

7 arcseconds to 400 keV36 arcseconds to 20 MeV

Temporal Resolution Tens of ms for basic image2 s for detailed image

Field of View Full Sun Effective Area - cm2 10-3 at 3 keV, 1 at 10 keV

100 at 100 keV, 50 at 10 MeV Numbers of flares ~1000 imaged to >100 keV.

~100 with spectroscopy to ~10 MeV

A1309.010

HESSI SummaryHESSI SummaryInstrument 9 germanium detectors (7-cm dia. x 8 cm)

Cooled to 75 K with Sunpower coolerGrid pitches from 34 microns to 2.75 mm1.5-m grid separationSolar Aspect System to <1 arcsecondRoll Angle System to 1 arcminute

Weight 120 kg Power 110 watts Telemetry <11 Gbits/daySpacecraft Spinning at 12 - 20 rpm

Pointing to within 0. 1° of Sun centerLaunch Vehicle SELV(TBD)Orbit 38° inclination

600 km altitude, >3-year lifeLaunch Date mid-2000Operations 3 years

A1309.011

HESSI PI and Co-IsHESSI PI and Co-IsRobert Lin University of California, Berkeley PI

Brian Dennis GSFC/682 Mission ScientistCarol Crannell GSFC/682 Education & Outreach Gordon Holman GSFC/682 Flare TheoryReuven Ramaty GSFC/661 Flare TheoryTycho von Rosenvinge GSFC/661 ACE Collaboration

Patricia Bornmann NOAA GOES CollaborationRichard Canfield Montana State University Ground-based ObservationsGordon Emslie Huntsville Flare TheoryHugh Hudson Solar Physics Research Corp. ImagingGordon Hurford Caltech ImagingNorman Madden LBNL Germanium Detectors

Arnold Benz Inst. of Astronomy, Zurich, Switzerland Radio ObservationsJohn Brown Univ. of Glasgow, Scotland Flare TheoryShinzo Enome NAO, Japan Radio ObservationsTakeo Kosugi NAO, Japan ImagingFrank van Beek Delft Univ., The Netherlands Grids and ImagingNicole Vilmer Observatoire de Paris, Meudon, France Data AnalysisAlex Zehnder Paul Scherrer Inst. Switzerland Telescope design

and fabrication

A1309.012

HESSI Prime ResponsibilitiesHESSI Prime Responsibilities

UC Berkeley Germanium detectors & electronicsI & TGround station, MOC/SOCData Analysis

GSFC Grid characterization & testingCooler, cryostat designData analysis, distribution, and

archivingPSI (Switzerland) Telescope & aspect systemJPL Finest grids (#1 & 2)van Beek (The Netherlands) Coarser grids (#3 - 9) & mountsSpectrum Astro Spacecraft

A1309.013

GSFC InvolvementGSFC InvolvementScience

Dennis (682) Mission ScientistHurford (Caltech) Imaging ScientistHolman (682), Ramaty (661) Solar flare physicsAschwanden (UMd) X-ray interpretationvon Rosenvinge (661) ACE/HESSI coordinationCrannell (682) Education & Public Outreach

ImagingClark (750), Amato (686) Grid environmental testingOrwig (682), Lang (CUA), Uribe (HSTX) Optical & X-ray grid characterizationSchmahl (UMd) Image reconstruction

SpectrometerBoyle (713) Cryostat design, cooler evaluationProvide flight-qualified Sunpower coolerSchwartz (HSTX) Spectral deconvolution

Data AnalysisGurman (682), Zarro (ARC) Solar Data Analysis CenterTolbert (HSTX) Data archiving and distribution

A1309.014

Test Fine GridsTest Fine Grids

A1309.015

Germanium DetectorGermanium Detector

A1309.019

Sunpower M77 Stirling-Cycle CoolerSunpower M77 Stirling-Cycle Cooler

A1309.020

Instrument SensitivityInstrument Sensitivity

A1309.021

Angular Coverage vs. Photon EnergyAngular Coverage vs. Photon Energy

A1309.022

Relative Modulation AmplitudeRelative Modulation Amplitudevs. Photon Energyvs. Photon Energy

A1309.023

Energy Resolution vs. Photon Energy Resolution vs. Photon EnergyEnergy

A1309.024

Count Rates in Each Detector Count Rates in Each Detector for One Rotationfor One Rotation

A1309.025

Prelaunch Twist Monitoring Prelaunch Twist Monitoring System (TMS)System (TMS)

A1309.026

A1309.027