1. Test Beam Experiment T-489 Measurements of Induced Activities and Residual Dose Rates
J. Bauer, V. Bharadwaj, H. Brogonia, A. Fasso, M. Kerimbaev, J. Liu, S. Rokni, T. Sanami, J. Sheppard, H. Tran (SLAC) M. Brugger, S. Mallows, S. Roesler, H. Vincke (CERN)

2. Motivation
Strong activation of beamline components and surrounding environment at LCLS (e.g., dump) and future Linear Colliders (e.g., beam delivery system, positron target, and beam dumps)
elevated residual dose rates – dose to personnel
activation of environment (groundwater, soil, air) – dose to population
activation of material – production of radioactive waste
structural damage of materials – degraded machine performance, repair
Optimization of design is essential to keep impact on personnel, facility operations and decommissioning, and environment (and associated costs) ALARA
Monte Carlo codes are used to predict induced activity
but: lack of experimental data for benchmarks (FLUKA, MARS, GEANT)

3. Goal Provide experimental data to benchmark activation predictions for
electron accelerators by Monte Carlo codes
First benchmark of a new method to calculate residual dose rates
with FLUKA at an electron accelerator
Combined benchmark of induced radioactivity and residual dose rates
Benefit from similar, limited experiments performed at SLAC and a hadron accelerator (CERN)

4. Monte-Carlo calculation: LCLS 13.64 GeV, 5 kW electron line
Elevation view
Elevation view
NEH
NEH
FEE
FEE
13.64GeV, 5kW
1 mrem/h
10 mrem/h
100 mrem/h
0.1 mrem/h
0.01 mrem/h
1 rem/h
Prompt dose rate
13.64GeV, 5kW
1 mrem/h
10 mrem/h
100 mrem/h
0.1 mrem/h
0.01 mrem/h
1 rem/h
Prompt dose rate
By MARS15 Geometry plotter
By MARS15 Geometry plotter
concrete
Elevation view
iron
Residual dose rate
concrete
Elevation view
iron
Residual dose rate
13.64GeV, 5kW
Ground water activity
System failure Analysis

5. ILC Positron Target Activation J.Sheppard, V.Bharadwaj
Preliminary calculations using FLUKA shows activation levels in range of 100 R/hr inside tunnel
Remote handling needed
Need good estimation of the activation field of the target hall
* too high leads to over-design and increases construction costs
* too low lead to operational risk and loss of performance
Can use FLUKA to design shielding to reduce activation fields in the target hall, reducing construction costs, operational costs and operating risk
Experimental benchmarking of FLUKA (and other codes) critical for believable estimation of activation
Schematic for Remote Handling Concept for ILC Positron Source Target Station

6. Hadron Accelerator Activation Study
One experiment was conducted at ESA by SLAC-RP and results were published in NIM (2002), which identified several improvements needed in measurements and Monte Carlo codes.
Several benchmark studies were performed at hadron accelerators
(CERN) during the past five years (collaboration between SLAC and
CERN RP-groups)
Results have triggered model developments with impressive
improvements for hadron machines (from factors of 2-5 in the past to ~20% at present)
Wide and successful application of these models for Large Hadron
Collider studies, proof of model performances was requested by
supervising authorities
This SLAC benchmark study will be performed in complete analogy !

7. Accelerator Activation Study - References
SLAC:
S.Rokni, A.Fasso, T.Gwise, J.Liu, S.Roesler
Induced radioactivity of materials by stray radiation fields at an electron accelerator
Nuclear Instruments and Methods in Physics Research A 484 (2002)
CERN:
M.Brugger, A.Ferrari, S.Roesler, L.Ulrici
Validation of the FLUKA Monte Carlo code for predicting induced radioactivity at high-energy accelerators
Nuclear Instruments and Methods in Physics Research A 562 (2006)
M.Brugger, H.Khater, S.Mayer, A.Prinz, S.Roesler, L.Ulrici, H.Vincke
Benchmark studies of induced radioactivity produced in LHC materials, Part I: Specific activities
Radiation Protection Dosimetry 116 (2005) 6-11
Benchmark studies of induced radioactivity produced in LHC materials, Part II: Remanent dose rates
Radiation Protection Dosimetry 116 (2005) 12-15
J.Vollaire, M.Brugger, D.Forkel-Wirth, S.Roesler, P.Vojtyla
Calculation of water activation for the LHC
Nuclear Instruments and Methods in Physics Research A 562 (2006)

8. Hadron Accelerator Activation Study – Specific Activities
Ratio FLUKA/Exp
0.8 < R < 1.2
0.8 < R ± Error < 1.2
Exp/MDA < 1
R + Error < 0.8 or
R – Error > 1.2

9. Hadron Accelerator Activation Study – Residual Dose Rates

10. Machine Requirements for T489
Momentum: GeV/c
Intensity: > 109 / pulse (approximately 100 W at 10 Hz)
Space: approximately 1 meter along beamline
Beam monitoring: accurate record (<10%) of integrated intensity and
history profile
Beam alignment: relative alignment to target within about 1 mm
Duration: shifts, 3 shifts per day (5 1/3 days)

11. Resources Equipment: Manpower: beam dump (SLAC, available)
supports for dump and samples (SLAC)
material samples (CERN)
beam intensity monitoring (SLAC, available)
dose rate instruments (CERN / SLAC, available)
gamma spectrometry (SLAC, available)
Manpower:
1 CERN student, Marie-Curie Fellowship Programme
3 CERN RP staff physicists
3 SLAC RP+ILC staff physicists
2 SLAC RP technicians