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P152 Experiment: Heavy Ion Interactions in Medical Applications

This article discusses the P152 Experiment, which aims to collect data on heavy ion interactions in ion therapy and space laboratories using the HEP emulsion chamber technology. The experiment involves 12 institutes from the HEP, medical, and space domains and utilizes the emulsion chamber for its high spatial resolution and charge identification capabilities. The article also highlights the preliminary results and ongoing comparison with simulation packages.

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P152 Experiment: Heavy Ion Interactions in Medical Applications

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  1. Carbon Physics ValidationP152 Experiment at NIRSGeant4 Workshop@LisbonParallel Session: Medical Applications12 October, 2006 Katsuya Amako(KEK)

  2. The P152 Experiment • Not many data available • Probably due to the poor availability of machines for experiments. • To understand physics of interactions is secondary importance for medical doctors(?) • Causes difficulty in Geant4 physics validation Albeit its importance, a systematic accumulation of ion interaction data relevant to ion-therapy has not been established yet. Why not to do an experiment by ourselves? We started the P152 experiment at NIRS.

  3. The P152 Experiment- cont’d Purpose: • To collect data of heavy ion interactions with H, C, O, Ca, P, etc in the energy region of ion therapy with the HEP emulsion chamber technology. • Also to collect data of heavy ion interactions which are important in the radiation shielding of space laboratories. Organization: • 12 institutes from HEP, medical and space domains • High Energy Accelerator Research Organization (KEK) • Nagoya Univ. • Ritsumeikan Univ. • Kobe Univ. • Naruto Univ. of Education • Toho Univ. • Aichi Univ. of Educaiton • Univ. of Tokyo • SLAC • National Institute of Radiological Science (NIRS) • Gunma Univ., Faculty of Medicine • Japan Aerospace Exploration Agency (JAXA) • Experiment - 1st Phase: 2002 - 2004 HEP Medical Space

  4. Experiment Areas Ion Source RFQ Linac 800 KeV/u Alvarez Linac 6 MeV/u Synchrotron 800 MeV/u Treatment Rooms ~65 m HIMAC/NIRS/Chiba/Japan • Operation since 1994 • About 1,800 patients treated • Treatment beam: 12C

  5. Example of Emulsion Chamber ~ 13 cm Why Emulsion Chamber? • 4p acceptance • High spatial resolution ( ～1μm) • Can record a very short track • Can do charge identification • No active parts in the detector • Easy to handle • Compact Harp Experiment ps214@CERN • 4p Measurement of Proton (2GeV~15GeV) Interactions with Nuclei • TPC • Forward Spectrometer • Gas Cherenkov • ToF, etc Target material sandwiched with emulsion films Not a fair comparison but you can get some feeling of emulsion chamber …

  6. Carbon Beam 180MeV/u 150μm Emulsion Film • Single sheet of emulsion film (Opera Film) • Film developed Thickness 293 mm 10 cm 12.5 cm • Film cross section 205μm Film Base (TAC) 44μm Emulsion Layer

  7. Water-Emulsion Chamber Multi-layers of emulsion films in a water chamber 27 cm Carbon Beam 27 cm 40 cm

  8. 430MeV/u 12C 12,000 tracks 4,000 events Tracks Reconstruction in Water-ECC Automatic scanning machine developed at Nagoya Univ. • For heavy ion tracks: • Spatial resolution ～1μm • Angular resolution ～5mrad • Track Finding Efficiency ～100%(tanθ≦0．4) • Automatic scanning speed: • ~ 10 hours/plate (Depends on the density of tracks) All reconstructed tracks in the water ECC An event selected from the left data 2 cm ~22 cm

  9. no refresh 30℃ 38℃ He 290 MeV/u 40℃ Li 45℃ Be B C Ion Charge Identification: Refresh Method • Refresh method • A new technique we’ve developed for this experiment – See our NIM paper(*) • Charge ID by the ‘grain’ density of a track – a higher charge causes saturation • The ‘refresh’ method expands the linearity of the ‘grain’ density. • After an exposure of films to the beam, put them in a high temperature/humidity environment. (Ex. 3 days under 38℃ relative humidity 98%) (*) Reference T. Toshito, et al., NIM A 5556, 482 (2006)

  10. Sheet A No refresh Sheet B Refreshed 40℃ Sheet D Refreshed 38℃ Schematic View of Emulsion Cloud Chamber P152 Experiment - December 2004 Beam - 12C 400 MeV/u

  11. C B Pulse Height 40℃ Be Li He Pulse Height 38℃ Charge Identification of Secondaries • Pulse Height Correlation • Refreshed 38℃ vs. 40℃ • Pulse Height of Track near Vertex Open circle Refreshed 40℃ Black sqares Refreshed 38℃ [Note] • We can identify the vertex by the change of pulse height • Enable us to measure very forward scattering

  12. Some Preliminary Results Total Charge Changing Cross Section (Carbon-Water) Angular Distribution of Secondaries Number of Tracks p Partial Charge Changing Cross Section (Carbon-Water ) B He C ➔ B Li Be Emission Angle (tan) C ➔ Be C ➔ Li

  13. Summary • The objective of the P152 experiment is to provide a systematic data set of ion interactions with matter for validation of Geant4 physics implementation. • It utilizes the emulsion chamber technique, which provides a simple and elegant detector system. • We have proved that the technique can be applied to identify ion tracks and their charges. • The P152 experiment is ready to publish the first data in public. • We are now working on comparison of our data with Geant4 and other simulation packages.

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