Energy dependence of DPA damage in SC coils and figure of ... · DPA as a function of beam energy 7...

Energy dependence of DPA damage in SC

coils and figure of merit for Mu2e @ PIP-II

Vitaly Pronskikh

RESMM’15, FRIB, East Lansing, Michigan

12 May 2015

Mu2e@PIP-II upgrade plans

• Early next decade

• 250 meter linac

• 800 MeV proton beam

(2 mA)

• -> Booster -> 8 GeV

(120 kW)

• -> Main

Injector/Recycler

• ->120 GeV (1.2 MW)

5/11/2015 2 Vitaly Pronskikh | Energy dependence of DPA damage in SC coils

Performance Parameter PIP PIP-II

Linac Beam Energy 400 800 MeV

Linac Beam Current 25 2 mA

Linac Beam Pulse Length 0.03 0.5 msec

Linac Pulse Repetition Rate 15 15 Hz

Linac Beam Power to Booster 4 13 kW

Linac Beam Power Capability (@>10% Duty Factor)

4 ~200 kW

Mu2e Upgrade Potential (800 MeV) NA >100 kW

Booster Protons per Pulse 4.2×1012 6.4×1012

Booster Pulse Repetition Rate 15 15 Hz

Booster Beam Power @ 8 GeV 80 120 kW

Beam Power to 8 GeV Program (max) 32 40 kW

Main Injector Cycle Time @ 120 GeV 1.33 1.2 sec

LBNF Beam Power @ 120 GeV* 0.7 1.2 MW

LBNF Upgrade Potential @ 60-120 GeV

NA >2 MW

Table from S.Holmes, Neutrino Summit, 2014

Baseline Mu2e and MARS15 simulations

• 8 GeV 8 kW proton beam

• Au target L=16 cm D=0.6 cm

(beam σ=0.1 cm)

• Bronze HRS (tungsten

considered for upgrade)

• PS, TS, DS (17-foil Al stopping

target)

• In MARS15 simulations:

LAQGSM, thresholds: 1E-12

GeV for neutrons, 100 keV for

charged h., muons, photons

5/11/2015 3

DPA and power density vs beam energy vs HRS material Muon yield/stopping rate vs beam energy Figure of merit (stopping rate per DPA)

Vitaly Pronskikh | Energy dependence of DPA damage in SC coils

DPA limit and model

5/11/2015 Vitaly Pronskikh | Energy dependence of DPA damage in SC coils 4

HRS: Bronze, Tungsten, Stainless (?) DPA model: NRT (below 20 (150) MeV ENDFB-VII/NJOY based cross section library FermiDPA 1.0) is used. NbTi coils DPA limits incorporate KUR measured data 4-6E-5 DPA

HRS thickness increase possibilities


K.Lynch and J.Popp Muon yield change with liner radius

Inner bore radius=20 cm No yield drop for R>17 cm

Power density and other limits


Talk at NuFact’12, July 23-28, 2012, Williamsburg

Power density limit: -depends on the cooling scheme -involves many other assumptions Dynamic heat load limit: -scales with the number of cooling stations Absorbed dose limit: usually high

DPA as a function of beam energy

5/11/2015 7

0 1 2 3 4 5 6 7 8 93.0x10

-6

4.0x10-6

5.0x10-6

6.0x10-6

7.0x10-6

beam power 1 kW

DP

A, yr-1

Ge

V-1

DPA

Power density

Tp, GeV

Bronze absorber

1.0x10-3

1.2x10-3

1.4x10-3

1.6x10-3

1.8x10-3

2.0x10-3

2.2x10-3

2.4x10-3

2.6x10-3

2.8x10-3

3.0x10-3

Po

we

r d

en

sity, m

W/g

/Ge

V


DPA damage and peak power density are: Largest at ~3 GeV and drops with energy below that energy Larger for bronze than for tungsten by a factor of ~3-4

DPA and power density @ 100 kW

• DPA: Current coil design can tolerate 100 kW at proton

energies < 1 GeV.

• Power density: different cooling scheme may be required.

• Above 1 GeV (DPA) or 2 GeV almost flat with energy.

5/11/2015 8

0 1 2 3 4 5 6 7 8 90

1x10-4

2x10-4

3x10-4

4x10-4

5x10-4

6x10-4

7x10-4

8x10-4

Bronze HRS

Tungsten HRS

DP

A, yr-1

Tp, GeV

100 kW beam power

0 1 2 3 4 5 6 7 8 90.0

2.0x10-2

4.0x10-2

6.0x10-2

8.0x10-2

1.0x10-1

1.2x10-1

1.4x10-1

1.6x10-1

1.8x10-1

2.0x10-1

2.2x10-1

2.4x10-1

Bronze HRS

Tungsten HRS

Po

we

r d

en

sity,

mW

/g

Tp, GeV

100 kW beam power


Mu- spectra and yields at TS

5/11/2015 9

1,E-11

1,E-10

1,E-09

1,E-08

1,E-07

1,E-06

1,E-05

1,E-04

0 50 100

N

p, MeV/c

Mu- momentum spectra at TS

0.5 GeV 3 GeV 8 GeV 0 1 2 3 4 5 6 7 8 9

10-3

10-2

p

er

pro

ton

Tp, GeV

- entering TS


Constant beam intensity (not power) = 6 · 1012 p/s Steepest rise in µ− yields is between 0.5 and 2 GeV.

Acceptance

At 0.8 GeV Average 1-8 GeV

Calculated using G4beamline, used with MARS15 calculated

muon spectra at TS


Mu- stopping rates and Figure of Merit

• 3 years = 3.6E20 protons on target

• If only stopped muons are taken into account: 2-3 GeV

• If also DPA is accounted for: 1-3 GeV is optimal

• FOM : 0.8 GeV is at least as good as 8 GeV

5/11/2015 11

0 1 2 3 4 5 6 7 8 9

1x1019

2x1019

3x1019

4x1019

sto

pped

-

Tp, GeV

- stops, 3yr @ 100 kW

0 1 2 3 4 5 6 7 8 91E21

1E22

Bronze HRS

Tungsten HRS

FO

M (

sto

pp

ed

- /D

PA

)

Tp, GeV


Conclusions

• Energy dependence of DPA damage, power density,

muon yield and muon stopping rate is studied.

• Figure of Merit (stopped muon to DPA ratio) is

proposed.

• Current coil/ tungsten HRS design can tolerate 100

kW @ energies < 1 GeV.

• FOM is largest in the 1-3 GeV range.

• FOM for 0.8 GeV is slightly better than for 8 GeV.


Energy dependence of DPA damage in SC coils and figure of ... · DPA as a function of beam energy 7...

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