1. Beam-Line Analysis
m. apollonio
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2. MC (G4Beamline)
DATA M
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3. MC (G4Beamline)
DATA M
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5. Characterizing the BL  MATRIX
Intensive Program (started in June with CR as MoM)
Choose Range of Momenta  initial optics: M0
scan of the DS triplets (and single Q4,..Q9) for some relevant optics
define variation of Twiss Parameters as a function of optics
MC simulation
DATA Analysis
Comparison
Optimize M0  Mopt: awesome or awful?
(*) 700mV ~ 20 mu-/spill
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6. The BL can be thought as constituted by TWO blocks:
US (=PIONS) and DS (=MUONS)
BL momentum scale is a pair of values
(P0 = momentum at target, PSol= momentum at Decay Solenoid exit, or D2)
P0 defines the momentum scale for PIONS
PSol defines the momentum scale for MUONS
Momentum scale(s) must match the US Diffuser face values
 initial optics: M0
easy, once defined Pdif we can work back Psol and P0 through
the tables. However the Twiss parameters at Diffuser are “random”
Recall also the main philosophy in defining (P0, Psol)
select Psol such that BACKWARD GOING muons are captured
so increase PURITY
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7. m kinematic limits 350 MeV/c 195 MeV/c m @ the Dksol exit (G4Beamline)
6-240
the Dksol exit (G4Beamline)
10-240
6-200
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8. 3,140 Pdif=151 a=0.2 b=0.56m t=0.0mm 3,200 Pdif=207 a=0.1 b=0.36m
P(MeV/c) e
140
200
240 3
Ptgt=321.3/Psol=185
Pdif=151
a=0.2
b=0.56 m
t=0.0 mm
Ptgt=390/Psol=231
Pdif=207
a=0.1
b=0.36 m
Ptgt=453.6/Psol=265
Pdif=245
b=0.42 m
t=0.0mm 6
Ptgt=327.6/Psol=189
Pdif=148
a=0.3
b=1.13 m
t=5.0 mm
Ptgt=408.6/Psol=238
Pdif=215
b=0.78 m
t=7.5 mm
Ptgt=471.6/Psol=276
Pdif=256
b=0.8 m
t=7.5mm 10
Ptgt=338.4/Psol=195
Pdif=164
a=0.6
b=1.98 m
t=10 mm
Ptgt=429.3/Psol=251
Pdif=229
a=0.4
b=1.31 m
t=15.5 mm
Ptgt=486/Psol=285
Pdif=267
b=1.29 m
3,140
Pdif=151
a=0.2
b=0.56m
t=0.0mm
3,200
Pdif=207
a=0.1
b=0.36m
t=0.0mm
3,240
Pdif=245
a=0.1
b=0.42m
t=0.0mm
6,140
Pdif=148
a=0.3
b=1.13m
t=5.0
6,200
Pdif=215
a=0.2
b=0.78m
t=7.5mm
6,240
Pdif=256
a=0.2
b=0.8m
t=7.5mm
10,140
Pdif=164
a=0.6
b=1.98m
t=10mm
10,200
Pdif=229
a=0.4
b=1.31m
t=15.5mm
10,240
Pdif=267
a=0.3
b=1.29m
t=15.5mm
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9. This pair is our goal: how do we get it?
P (MeV/c)
3,140
3,200
3,240
finding the element (3,240) means to find the BL optics that matches the MICE optics for a beam of 3 mm rad at a P=240 MeV/c
6,140
6,200
6,240
eN (mm rad)
the element (10,200) is the BL optics matching a MICE beam with 10 mm rad at P=200 MeV/c
10,140
10,200
10,240
This pair is our goal: how do we get it?
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10. Hyp.: eN0 is known (~1 mm rad trace space) we proceed backward:
fix P/eN in the cooling channel
fix the optics in the cooling channel (a3,b3)
solve the equations giving a,b and t at the US face of the diffuser (*) b0 a0
Diffuser b1 a1 b2 a2 b3 a3 t BL
MICE e1
(*) MICE note 176 e0
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11. m p So the question becomes:
how do we “tell” the beamline to be a0, b0 at US_Diff?
solution(s)
we optimise the BL by varying Q4-Q9
let us break the BL in two parts: US and DS
in what follows I mean a p m beamline
DS part:
choose Q4-Q9
shoot a beam
check a,b at Diffuser vs “target” values
repeat m Q4 Q1
Dipole1
DK solenoid Q2 Q3
Dipole2 Q5 Q6 Q7 Q8 Q9 p
US part: we can optimise the MAX number of pions
but not much magic left …
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12. p  m beam line: typical m spectrum at the exit of the DS
Rationale
select p u.s. of DKSol with D1
select m d.s. of DKSol with D2
back scattered muons == purity
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13. we already have an initial solution: the “central value”
Key Point
materials in the BL cause energy loss
(also emi_growth)
in order to have P_mice=200 MeV/c we need to define P_D2 properly
then we define Ppi_tgt
how?
the best choice is dictated by beam purity
3,140
3,200
3,240
6,140
6,200
6,240
10,140
10,200
10,240
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14. In the original scheme the pi  mu beamline is Ppi=444  Pmu=256
Best separation PI/MU
p acceptance
Will it work?
Pdiff = 215
NB.: PD2=256 MeV/c becomes
Pdif=215 MeV/c
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15. i.o.t. accommodate several mu momenta another “shortcut” scheme was adopted (aug 2009):
Define one lower Ppi ~ 350/360 and several different Pmu (we lose in purity …)
p acceptance
Pdiff =
Ppi (tgt) = 350
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16. d.s. BL tuning: match to diffuserQ4 Q1
Dipole1
DK solenoid Q2 Q3
Dipole2 Q5 Q6 Q7 Q8 Q9
Pp=444 MeV/c
Pm=255 MeV/c
Pm=214 MeV/c
Pm=208 MeV/c
fix D1
fix D2 p
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17. - a first round of the BL optimised (e,P) matrix has been produced
in august 2009 (“shortcut”)
however the few data taken in november
reveal a pretty strange look
one thing I dislike is using only one
momentum for the pion (US) component and
Select the backward going muons
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18.
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19. PI- (444MeV/c) MU- (256 MeV/c) at D2 PI- should be here: 30.44
~29.
RUN –
PI- (444MeV/c) MU- (256 MeV/c) at D2
PI- should
be here: 30.44
NB: DTmu(256)= DTmu(300) * beta300/beta256
= * .943/.923 = 29.13
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20. ? PI- should be here: 30.44 RUN 1201 –
PI- (336.8MeV/c) MU- (256 MeV/c) at D2
MU- should be the same as
before … what is that?
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21. (arbitrary statistics)
G4Beamline
Generation up
To DS
Generate
Gaussian
Beam with
defined
COV-MAT
(arbitrary statistics)
COV-MAT x’ x y’
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22. wrap-up …
Consider all 9 cases: one Ppi + one Pmu per case (no “shortcuts”)
Define initial BL currents (from scaling tables)
Check tuning with G4Beamline
use simulation output at DS to infer the COV-MAT of the beam
Generate a Gauss-beam with that CovMat:
E.g. MatLab tool, fast + any number of particles …
Propagate / optimise this beam in the DS section
By hand (GUI tool)
By algorithm (GA)
check results versus real data …
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23. 7/7/2010
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