Activation Calculation for the Robinson Wiggler at the Metrology - PowerPoint PPT Presentation

Activation Calculation for the Robinson Wiggler at the Metrology Light Source Y. Bergmann, K. Ott Helmholtz- Zentrum Berlin yvonne.bergmann@helmholtz-berlin.de 9th Int. Workshop on Radiation Safety at Synchrotron Radiation Sources RADSYNCH 2017, NSRRC Taiwan

MAP OF THE AREA MLS bERLinPro BESSY II RadSynch 2017, NSRRC, Taiwan 2

OUTLINE  Overview Metrology Light Source  Development of the Robinson Wiggler  Activation Calculation  Calculation with FLUKA  Summary and Outlook RadSynch 2017, NSRRC, Taiwan 3

OVERVIEW MLS Undulator U125 Injection Septum MLS – KEY FIGURES Cavity Energy E [MeV] 50 to 629 Circumference [m] 48 Transfer line Microtron Beam Current I [mA] 1e-9 to 200 Beam Lifetime (150 mA) [h] 6 Cavity Voltage [kV] 500 Horizontal Emittance [nm rad] 117 Magnetic Field B [T] 1.3 Bending Radius R [m] 1.5 RadSynch 2017, NSRRC, Taiwan 4

A ROBINSON WIGGLER FOR THE MLS  lifetime (Lt) fundamental for users of synchrotron radiation  2012 Standard user optic at MLS: Lt = 3,5 h at 150 mA  2014 change magnet optics  new user optics: Lt = 6 h at 150 mA  lifetime at MLS dominated by Touschek effect  to increase lifetime  improve Touschek lifetime  Touschek lifetime depends on bunch size and length  Redistributing damping partition of beam  incr. bunch length  incr. Lt  Solution for existing accelerator  ID consisting of alternating combined function magnets Robinson Wiggler RadSynch 2017, NSRRC, Taiwan 5

A ROBINSON WIGGLER FOR THE MLS  1 available straight section at MLS  section of 2.5 m lengths Robinson Wiggler max. 1.74 m Gray: ferromagnetic yoke, copper: coils Poles have hyperbolic shape in horizontal direction, giving rise to linear, horizontal field gradient  Design studies show: • normal conducting Robinson Wiggler will consist of twelve poles, incl. endpoles • to achieve necessary high field strengths use Cobalt-Iron steel (AFK502) for yoke • AFK502: compound of 49% Fe, 49% Co, and 2% V RadSynch 2017, NSRRC, Taiwan 6

MOTIVATION – ACTIVATION AT ACCELERATORS Activation is a serious hazard since the radiation remains after switching off the accelerator. Consequences: Additional radiation exposition at electron accelerators Bremsstrahlung and electron losses induce gamma-radiation  leads to neutron radiation and activation thermal neutrons  activation? RadSynch 2017, NSRRC, Taiwan 7

MOTIVATION – CROSS SECTION σ (n, γ ) Amount in yoke (25 meV) Fe 49% 2.6 barns Co 49% 37.2 barns V 2% 4.8 barns High amount of Cobalt might get activated by beamloss  Neutron cross section express likelihood of interaction between incident neutron and target  Thermal neutrons of great importance: cross section decrease by increasing kinetic energy RadSynch 2017, NSRRC, Taiwan 8

ACTIVATION CALCULATION Activation rate: Activation rate can be calculated by FLUKA (1) σ (E P ): cross section E P : energy of photons Φ (E P , r) . dE P : flux density of photons with energies between E P and E P +dE at r n= ρ . N L /A: number of nuclei per volume ρ : density of nuclei N A : avogadro constant = 6.022 E23 mol -1 A: mass number of nucleus Activation Equation: (2) = 1 for one radiation period ν : number of irradiation periods λ = (ln2)/T 1/2 (T 1/2 : half-life of nucleus) t B : irradtiation time t K : decay time RadSynch 2017, NSRRC, Taiwan 9

CALCULATION OF DOSE OF KNOWN REACTION 59 Co + n  60 Co *  60 Co + γ  Assumption: cross section of Co predominantly for interaction with neutrons N 0 = 1.6 E9 neutrons/year/yoke calculated by Fluka N (x) N 0 N N ~ N 0  „method by hand“:  t B =1 year, t K = 0 Activation (2) A v = 3.12 Bq / cm 3 With  N = 25 neutrons / sec  λ ( 60 Co)=4.17 E-9 / sec  distance r of 10 cm With  mSv m ²  Γ ( 60 Co) = 0 . 354  h [ GBq ] RadSynch 2017, NSRRC, Taiwan 10

FLUKA CALCULATION: PRELIMINIARY CONSIDERATIONS  200 mA / injection  1800 injections / year  revolution frequency 6.25 MHz  Injection efficiency ~ 20% Loss of ~ 18 E14 electrons / year RadSynch 2017, NSRRC, Taiwan 11

FLUKA CALCULATION: OUTPUT For every region of interest: generated resnucle-file Fluka Output in residual nuclei / pP code (aktiv2 by K. Ott) which identifies radionuclides (> 200) with A and Z and its activation Output: list of radionuklides and its activation RadSynch 2017, NSRRC, Taiwan 12

A∞ A∞ RESULTS: RADIONUCLIDES AND ACTIVATION A∞ Nuklid NK A(t) T (1/2) 1 _ 1 H 2,59E-06 8,21E+00 8,21E+00 stabil 2 _ 1 H 2,45E-08 7,77E-02 7,77E-02 stabil 3_1H 2,94E-09 9,33E-03 5,10E-04 12.323 a 4 _ 2 He 3,34E-07 1,06E+00 1,06E+00 stabil A∞ Nuklid NK A(t) T (1/2) 46 _ 20 Ca 3,05E-10 9,68E-04 9,68E-04 stabil 47 _ 21 Sc 6,11E-10 1,94E-03 1,94E-03 3.35 d 1 _ 1 H 2,59E-06 8,21E+00 8,21E+00 stabil 49 _ 21 Sc 3,05E-10 9,68E-04 9,68E-04 57.2 min 47 _ 22 Ti 3,05E-10 9,68E-04 9,68E-04 stabil 2 _ 1 H 2,45E-08 7,77E-02 7,77E-02 stabil 48 _ 22 Ti 9,16E-10 2,91E-03 2,91E-03 stabil 3_1H 2,94E-09 9,33E-03 5,10E-04 12.323 a 49 _ 22 Ti 1,22E-09 3,87E-03 3,87E-03 stabil 50 _ 22 Ti 4,28E-09 1,36E-02 1,36E-02 stabil 4 _ 2 He 3,34E-07 1,06E+00 1,06E+00 stabil 51 _ 22 Ti 3,05E-10 9,68E-04 9,68E-04 5.8 m 48 _ 23 V 6,11E-10 1,94E-03 1,94E-03 15.97 d 46 _ 20 Ca 3,05E-10 9,68E-04 9,68E-04 stabil 49 _ 23 V 4,88E-09 1,55E-02 8,29E-03 330 d Beam 1 year 51 _ 23 V 5,49E-09 1,74E-02 1,74E-02 stabil 52 _ 23 V 1,53E-09 4,84E-03 4,84E-03 3.75 m no decay time 49 _ 24 Cr 3,05E-10 9,68E-04 9,68E-04 42 m 50 _ 24 Cr 4,01E-09 1,27E-02 1,27E-02 stabil 51 _ 24 Cr 2,59E-08 8,23E-02 8,23E-02 27.7 d 52 _ 24 Cr 5,02E-08 1,59E-01 1,59E-01 stabil 55 _ 24 Cr 6,11E-10 1,94E-03 1,94E-03 3.5 m 53 _ 24 Cr 1,13E-07 3,57E-01 3,57E-01 stabil 54 _ 24 Cr 5,24E-09 1,66E-02 1,66E-02 stabil 52 _ 25 Mn 6,71E-09 2,13E-02 2,13E-02 5.6 d 55 _ 24 Cr 6,11E-10 1,94E-03 1,94E-03 3.5 m 53 _ 25 Mn 6,14E-08 1,95E-01 3,65E-08 3.7e6 a 52 _ 25 Mn 6,71E-09 2,13E-02 2,13E-02 5.6 d 53 _ 25 Mn 6,14E-08 1,95E-01 3,65E-08 3.7e6 a 54 _ 25 Mn 5,82E-07 1,85E+00 1,03E+00 312.2 d 54 _ 25 Mn 5,82E-07 1,85E+00 1,03E+00 312.2 d 55 _ 25 Mn 2,00E-07 6,34E-01 6,34E-01 stabil 55 _ 25 Mn 2,00E-07 6,34E-01 6,34E-01 stabil 56 _ 25 Mn 3,13E-07 9,91E-01 9,91E-01 2.58 h 57 _ 25 Mn 3,09E-09 9,79E-03 9,79E-03 1.5 m 56 _ 25 Mn 3,13E-07 9,91E-01 9,91E-01 2.58 h 58 _ 25 Mn 3,05E-10 9,68E-04 9,68E-04 65.3 s 52 _ 26 Fe 3,05E-10 9,68E-04 9,68E-04 8.27 h 57 _ 25 Mn 3,09E-09 9,79E-03 9,79E-03 1.5 m 53 _ 26 Fe 7,23E-09 2,29E-02 2,29E-02 8.51 m 54 _ 26 Fe 2,50E-06 7,94E+00 7,94E+00 stabil 55 _ 26 Fe 7,93E-07 2,52E+00 5,64E-01 2.73 a 56 _ 26 Fe 6,96E-05 2,21E+02 2,21E+02 stabil 57 _ 26 Fe 9,07E-06 2,88E+01 2,88E+01 stabil 58 _ 26 Fe 6,66E-07 2,11E+00 2,11E+00 stabil 57 _ 27 Co 1,19E-07 3,77E-01 3,63E-01 271.79 d 59 _ 26 Fe 2,42E-07 7,67E-01 7,64E-01 44.503 d 56 _ 27 Co 6,10E-09 1,93E-02 1,86E-02 77.26 d 58 _ 27 Co 8,20E-07 2,60E+00 2,53E+00 70.86 d 57 _ 27 Co 1,19E-07 3,77E-01 3,63E-01 271.79 d 58 _ 27 Co 8,20E-07 2,60E+00 2,53E+00 70.86 d 59 _ 27 Co 7,64E-05 2,42E+02 2,42E+02 stabil 59 _ 27 Co 7,64E-05 2,42E+02 2,42E+02 stabil 60 _ 27 Co 3,21E-05 1,02E+02 1,25E+01 5.272 a 60 _ 27 Co 3,21E-05 1,02E+02 1,25E+01 5.272 a 61 _ 28 Ni 4,40E-10 1,39E-03 1,39E-03 stabil 61 _ 28 Ni 4,40E-10 1,39E-03 1,39E-03 stabil 62 _ 28 Ni 2,65E-09 8,40E-03 8,40E-03 stabil 63 _ 28 Ni 8,47E-09 2,68E-02 1,85E-04 100 a 62 _ 28 Ni 2,65E-09 8,40E-03 8,40E-03 stabil 64 _ 29 Cu 8,48E-10 2,69E-03 2,69E-03 12.7 h 65 _ 29 Cu 1,83E-09 5,81E-03 5,81E-03 stabil 66 _ 29 Cu 1,00E-08 3,18E-02 3,18E-02 5.1 m 64 _ 30 Zn 8,00E-09 2,54E-02 2,54E-02 stabil 65 _ 30 Zn 2,13E-08 6,75E-02 4,35E-02 244.3 d 66 _ 30 Zn 3,27E-06 1,04E+01 1,04E+01 stabil 67 _ 30 Zn 3,07E-07 9,72E-01 9,72E-01 stabil RadSynch 2017, NSRRC, Taiwan 13