Collection system optimisation for SPL at 3.5 GeV

Collectionsystem optimisation for SPL at 3.5 GeV

Antoine CazesLaboratori Nazionali di Frascati

November 14th, 2006

Antoine CazesAntoine CazesBENE meeting – November 14BENE meeting – November 14 thth 2006 - Frascati 2006 - Frascati

Overview:


Interaction between proton beam and target. Simulation done with FLUKA 2002.4 and MARS Proton beam

Ek=2.2GeV, 3.5GeV, 4.5GeV, 6.5GeV et 8GeV

Target Liquid mercury

Long : 30cm 15mm

Normalization: 4MW 1.1×1016pot/[email protected] 0.7×1016pot/[email protected]


Particle Producion

500 000 protons, Ek < 5GeV at 2.2GeV :

0.26 +/s 0.8 10-3 K+/s

at 3.5GeV : 0.29 +/s 2.8 10-3 K+/s

Ep(GeV) Ep(GeV)

+

-

K+

K-

K0

at 4.5GeV : 0.32 +/s 5.2 10-3 K+/s


Horn optimisation

Super Beam 130km beam Tunnel raduis

Neutrinos Factory Decay tunnel = solénoïde

px/pz

x

20 mrad

2 m

px/pz

x

0,5 rad

30 cm 2 105 potSB

Momentum At the target

Fact


Collector

•2 concentric horns•300kA et 600kA•Conductor thickness : 3mm

BB

•Particles exit with large angle:

•<> = 60°@2,2GeV•<> = 55°@3,5GeV

•Target must be inside the horn.

•Pion transvers momentum

+

-

PT(GeV/c) PT(GeV/c)

Horn + reflOnly hornNo focus


Horn design

•E ~ 350MeV(p = 800MeV/c)

•E ~ 260MeV(p = 600MeV/c)

2 optimisations studied :

Oscillation Maximum

B1

B2

x

NuFact Note 138


Horn design parameter

140 cm 220 cm

80 cm

E~300MeV

HORNHORN

inner radius 3.4cm

neck length 40cm

outer radius 20.5cm

total length 120cm

REFLECTOR

outer radius 40cm

total length 190cm

HORNHORN

inner radius 3.4cm

neck length 40cm

outer radius 20.5cm

total length 140cm

REFLECTOR

outer radius 40cm

total length 220cm

E~260MeVE~600MeV

E~300MeVE~800MeV

Conductor thickness : 3mmhorn : 300kAmpsreflector : 600kAmps


Energy deposition (Geant 3.2.1)

34.0 kW47kW

4MW, 2.2GeV

+7kW from Joule effect

13.6kW

Solution under investigation : reduce the Aluminium thickness (3mm Al) + strength rings.

63kW

(8mm Al)

NuFact Note 134


Decay Tunnel Parameters

Length modify purity L=10m, 20m, 40m and

60m have been tested. 10m40m

, + 50% to 70%

e , e + 50% to 100%

40m60m , + 5%

e , e + 20%

40m seems better

Radius modify acceptance R=1m, 1.5m and 2m have

been Tested 1m 2m (L=40)

, +50%

e , e +50% to 70%

2m seems better

This results have been checked on sensitivity to 13 and CP


Flux computation Low energy Small boost low focusing Need a high number of events (~1015 evts!!!) Use probability (M. Donega thesis approach)

Each time a pion, a muon, or a kaon is decayed by Geant, compute the probability for the neutrino to reach the detector

Use this probability as a weight, and fill an histogram with the neutrino energy

Gives neutrino spectrum.


Pion is tracked by Geant When it decays, The probability for the

neutrino to reach the detector is computed: (2-body decay)

P = 14AL2

1 – 2

(cos-1)2

L : distance to detectorA : detector surface

To reach the detector:

Probability method …. Pions


Probability method …. Muons ee

But muons have small decay probability. for each muon

loop on the phase space (,,E) compute decay probability e-x/c

if it decays, compute probability for the neutrino to reach the detector :

P = 14

AL2

1 – 2

(cos-12

2m

11 + cos

(f0(x) f1(x)cos

x = 2E/m

f0(x) f1(x)

2x2(3-2x) 2x2(1-2x)

e 12x2(1-x) 12x2(1-x)

is the muon polarisation coming from the pion/kaon decay


Probability method …. Kaons

Very few kaons : kaon produced in the target is duplicated

many times: ~100. Decay using Geant

Choose the decay channel Probability computed depending on the decay

channel 2 body decay 3 body decay


Neutrino flux @ 130km

•3.5GeV Kinetic proton beam•~800MeV focusing•~300MeV neutrinos•40m decay tunnel length•2m decay tunnel radius


Proton beam energy comparizon

E~260MeV

CP = 010-3 sin221

3

10-3

m2

23

(eV

2)

2.2GeV 3.5GeV 4.5GeV 8GeV

5 year positive focussing 10 years mixte focussing(8y + and 2y -)

3.5GeV better !!!

Campagne, Cazes : Eur Phys J C45:643-657,2006


Conclusion

Choice of the beam energy is delicate Tools exist to do another simulation

Proton interaction on target should be better with new version of fluka

Shape of the horns is crucial. Technical feasability should be taken into

account...

That’s all folks !!!


Project optimisation

2yrs (+)8yrs (-)

- Old result- New optimization

Campagne, Cazes : Eur Phys J C45:643-657,2006

mixte Focalisation Acces to CP

To balance: 20% positive 80% négative

Used values: CP=0, 13=0,

sin2212=0.82,

23=p/4, m221=8.1 10-5,

m231=2.2 10-3

5% precision on 12 and m221

d’un factor 4 Gain on the sensitivity

Documents

Collection system optimisation for SPL at 3.5 GeV