1. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 1 Gamma-Ray Astronomy From Balloons Jack Tueller Balloon Project Scientist

2. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 2 Gamma Rays Gamma rays are the highest energy photons. Gamma rays do not penetrate to the ground. Balloons can provide access to all energies >20 keV (Hard X-rays and Gamma Rays)

3. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 3 What makes suborbital different? Different Risk Management Strategy the payload is recovered re-flights are inexpensive ( $100M for a rocket) Higher Risk is the Best Strategy lower cost faster migration of new technology smaller more focused efforts training new workforce

4. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 4 Gamma-Ray Astronomy from Balloons atmospheric cutoff is 20keV no soft x-rays To get a high sensitivity gamma-ray payloads must be big and heavy gamma-ray payloads work best at low latitudes magnetic shielding low background gamma-ray payloads must be pointed real science is possible but we need LDB at low latitudes Boggs NCT GRIS ProtoEXIST InFOCuS GLAST HEFT

5. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 5 SN1987A first nearby supernova in 400 years every instrument possible was used many new phenomena were discovered balloons can provide quick access to space for timely measurements HST rings before after

6. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 6 High Resolution Spectroscopy In 1987 there were no high resolution germanium spectrometers in space like INTEGRAL Gamma-ray lines yield nuclear yields and velocity distribution that cannot be determined at other wavelengths Balloon experiments filled the gap GRIS, HEXAGONE, Lockheed Martin balloon's success leads to INTEGRAL GRIS INTEGRAL

7. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 7 SN1987A Lines Gamma ray line profiles are not distorted by complicated effects such as resonant scattering. Line profiles did not fit the standard models. Lines are red-shifted not blue-shifted. But, they validate the detailed IR line profiles. SN1987a was an asymmetric explosion! future: 44 Ti lines?

8. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 8 Nuclear Lines Nuclear lines are the unique signal of the production of new elements Boggs ACT Concept Study

9. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 9 Type Ia Supernovae Much Cosmology rests on using Type Ia's as a standard candle but the physics are not understood! Explosion is driven by radioactive decay. Boggs ACT study

10. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 10 Compton Scattering GRIS worked with large detectors to capture all the energy and a thick collimator (800 lbs of NaI) to isolate the source. Compton scattering is the dominant cross section between 200 keV and 2 MeV where most of the interesting gamma ray lines occur. Localizing all the interactions allows accurate reconstruction of the source positions and spectra over a wide field

11. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 11 Compton Telescopes Boggs NCT Development of an Advanced Compton Telescope several technologies are possible –Si & Ge strip detectors –Si & CdZnTe strip detectors –thick Si –Liquid Xe –Gaseous Xe-LaBr 3 –LaBr 3 All are now or are proposed balloon payloads ACT Concept

12. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 12 High Energy Gamma Rays Technology for EGRET developed on HEBE balloon experiment Go-no go test of GLAST technology on balloons Would the background rejection work? EGRET All-Sky >100 MeV GLAST balloon test bed detector CGRO/EGRET

13. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 13 absorbed (52) unabsorbed (49) Understanding Supermassive Black Holes How do black holes form and grow? What stops the growth? How do black holes effect galaxy formation? BAT XMM Only in hard x-ray can you find all the sources and measure their luminosity.

14. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 14 A hard X-ray all-sky monitor can make great advances in variability studies of black holes. A sensitive hard X-ray all- sky survey is the only way to find all the obscured sources. ProtoEXIST EXIST Swift/BAT Hard X-ray Survey >14 keV

15. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 15 Hard X-ray Focusing Optics multilayer grazing incidence focusing optics long focal lengths are required (InFOCuS is 8m) CdZnTe focal plane is the other critical technology. (A Si focal plane would be 1 cm thick.) Balloons can accommodate long focal lengths without costly mechanisms. Launch Sep 16, 2004 Ft. Sumner NM InFOCuS 9m No mechanism was required to launch 9m truss.

16. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 16 3 Balloon Instruments Three instruments are currently active: HEFT-CIT Columbia InFOCuS-GSFC Nagoya HERO-MSFC Each of these instruments test alternative technology for hard x-ray focusing optics. Proposed for Con-X enhancement and SMEX-NuSTAR InFOCuS HERO HEFT

17. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 17 The Black Hole at the Galactic Center A supermassive black hole lurks at the Galactic Center. Like most black holes at the center of galaxies it is a very weak source at all wavelengths. What is the accretion rate and why is it so low? The GC is a very crowded area. Only high resolution hard X- ray imaging can answer this question. INTEGRAL INTEGRAL imaging with >10 arcmin resolution is hopelessly confused. Soft X-ray imaging with Chandra sees 2000 sources <10 arcmin from the center.

18. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 18 What is the future? How do we maintain strong balloon science in this field? long duration flights at low latitude –super pressure balloon –trajectory modification system –long duration requires higher reliability - more cost and oversight advanced designs: bigger and heavier payloads secure and adequate funding

19. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 19 Workforce Replenishment How are future instrument builders recruited and trained? BALLOONS! fast enough for grad student to complete all phases of a project small enough for the university researcher open to hands-on student participation pushing newest technology produces significant science results Mission/ Instrument PI CGRO BATSE Fishman EGRET Fichtel INTEGRAL SPI Teegarden Matteson HEAO-3 Jacobson HEAO-1 Peterson

20. NASA GSFC WFF PSL CSBF SWRI Balloon Workshop Jack Tueller 20 Conclusions Gamma-ray astronomy could have a bright future in ballooning. Significant science can be achieved on balloons. Balloons are crucial to the development of new missions. Low cost ballooning can keep a field alive in hard times. Ballooning is the natural way to recruit and train a workforce. NASA and gamma-ray astronomy need a vigorous balloon program