RADIOPROTEZIONE DEGLI ASTRONAUTI DA RADIAZIONE COSMICA

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RADIOPROTEZIONE DEGLI ASTRONAUTI DA RADIAZIONE
COSMICA

• Gianfranco Grossi
• Dipartimento di Scienze Fisiche
• Università di Napoli Federico II
• INFN - Sezione di Napoli

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The places we will goif radiation doesnt hold
us back

Earth and LEO
The Earths Neighborhood
Accessible Planetary Surfaces
Outer Planets
Mars
The Moon
Earth-Moon L1
Asteroids or Other Targets...
Sun-Earth L2
Up to 180 days
L1
Risk of cancer lethality (4 ? 8) x 10-2 per Sv
L2
500 to 1000 days
gt 2000 days
Up to 100 days
Dose - rate 1 mSv/d
2 mSv/d
3 mSv/d
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The problem
Long-term interplanetary missions are planned in
the XXI century
Crews will be exposed to significant doses
delivered by high-energy charged particles, in
extreme conditions (stress, microgravity,..)
Uncertainties on radiation risk estimates in deep
space are between 400 and 1500
Uncertainty must be reduced for safe human
colonization of the solar system
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Best shielding materials

• Projectile interactions per unit target mass
• Ionization Z/A
• Fragmentation A-1/3

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HZE shielding

• Shielding of heavy ions is complicated by nuclear
  fragmentation
• Projectile fragmentation produces swift light
  ions and neutrons
• Target fragmentation produces slow, densely
  ionizing ions
• Fragments have different Q than primary ions

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GCR shielding - calculation by HZETRN
Aluminum 30 Polyethylene 50 Liquid hydrogen
90
Max GCR dose reduction
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The SHIELD experiment

• SHIELD started in 1999 4 Italian research
  Institutes, NASA JSC, BNL, and NIRS (Japan)
• Goal study of biological effects of heavy ions
  with shielding
• Results of experimental studies can be used to
  benchmark the codes
• Different biological endpoints (CA, SV, DNA DSB)
  shield materials (LDPE, PMMA, C, Al, Pb) and
  thickness (2 - 30 g/cm2), ion (H, C, Fe, Si, Ti)
  charge and energy (0.3 - 5 GeV/n)
• Results presented here are relative to the
  induction of chromosomal aberrations in human
  lymphocytes exposed to 56Fe projectiles with
  different shields

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Chromosomal aberrations measured by FISH in PCC
from human lymphocytes
Translocations involving chromosome ?4 (left)
and ? 2 (right). In light green chromosome ?1, in
red chromosome and in dark green chromosome ?4
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Nuclear fragmentation of AGS-BNL 56Fe beams
5 GeV/n 56Fe
5 GeV/n 56Fe 25 cm PMMA
CR39 nuclear plastic detector
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CA / 1 GeV/n 56Fe-particle vs. shield
thickness
Effectiveness per Fe-particle incident on the
shield is dependent on beam fragmentation, and is
determined by combination of dose/particle and
RBE-LET relationship
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In-flight shielding test

• Best candidate shielding materials from
  accelerator-based research should eventually be
  tested onboard against the whole spectrum of
  trapped and galactic radiation
• ESA has recently approved two experiments to
  study shielding in orbit using the detectors
  ALTEINO and MATROSHKA on International Space
  Station
• Two experiments (ESCHILO and RADIS) will flight
  in 2006-07 to test the shielding effectiveness of
  new composite materials and, for comparison,
  polyethylene.

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Shielding on ISS
Sleep station outfitted with polyethylene and
water Thin, flat panels are polyethylene
shields Stowage water packaging above the sleep
station
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ESCHILO(Esperimento di Schermatura in Low Orbit)

• Measurements of shielding on ISS (INFN,
  University Tor Vergata, Alenia Spazio, University
  Federico II)
• PI Marco Casolino
• Detector ALTEINO on ISS
• Shield two multimaterial tiles divided into 4
  sections

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RADIS (Radiation Distribution)

• Large (23 Institutes, led by DLR, Germany)
  scientific collaboration to use MATROSHKA inside
  the ISS (from May 2005)
• University Federico II is supposed to provide
  shielding materials to cover MATROSHKA and
  measure the changes in dose, flux, radiation
  quality, etc. at various depths in the phantom.

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Marco Durante Giancarlo Gialanella Gianfranco
Grossi Lorenzo Manti Mariagabriella
Pugliese Paola Scampoli