mucool experiment- plansagni.phys.iit.edu/~capp/workshops/muinst2000/raja.pdf · 2000. 12. 4. ·...

Nov 10,2000 Rajendran Raja,IIT Instrumentation workshop 1

MUCOOL experiment- Plans

Rajendran RajaFermilab

IIT instrumentation Workshop Nov 10,2000


Charge from Fermilab

Sep 13, 2000 letter from John Cooper to me states “I am asking you to lead the work at Fermilab on the following tasks:

1. Design of a muon testbeam that can be used to study the performance of a cooling section.

2. Simulation of the response of a cooling test section to the test beam. Hence determine what properties of the cooling channel can and cannot be tested in a muon beam.

I would like a short report on these items to be given to Mike Shaevitz, Steve Holmes and myself by April 1st, 2001”.

We have had 3 meetings on this topic. I will summarize the ideas generated therein.


Muon Test beam-Targetry

1 Targetry and Primary Focusing

(N.Holtkamp, N.Mokhov)

• 8 GeV proton beam (FNAL Booster)• Active target• Li lens for primary focusing

Li LensTarget1.6 cm

15 cm

8.5 cm

40 cm

Shield

Figure 1: Schematic of the target station.

Proton Beam: 8 GeV, σx = σy = 6 mm, σz = 30 cm, 750,000 protonsTarget: Copper, L = 15 cm, R = 1.6 cm, G = 4.39 T/cm,

Bmax = 7.0 T, J = 560 kALi Lens: L = 40 cm, R = 8.5 cm, G = 0.158 T/cm,

Bmax = 1.34 T, J = 570 kA

2


Muon Test beam-Decay channel

2 Beam Characteristics after Li Lens

Yield: π−/p = 0.119, µ−/p = 0.0022

0.0 0.2 0.4 0.6 0.8 1.0Total energy (GeV)

0.00

0.05

0.10

0.15

0.20

0.25

(π+µ

)/pro

ton/

GeV

Energy distribution of π−+µ− after Li lens Total π/p=0.119, µ/p=0.0022

Figure 2:

−20 −10 0 10 20X (cm)

−20

−10

0

10

20

Y (c

m)

X−Y phase space after Li lensCircle − acceptance of Q−channel

Figure 3:

−200 −100 0 100 200PX (MeV/c)

−200

−100

0

100

200

PY (M

eV/c

)

PX−PY phase space after Li lensCircle − acceptance of Q−channel

Figure 4:

−20 −10 0 10 20X (cm)

−200

−100

0

100

200

PX (M

eV/c

)

X−PX phase space after Li lensEllipse − acceptance of Q−channel

Figure 5:

3


Muon test beam – Decay channel

3 Q-Decay Channel: Lattice and β-functions

• Quads: L = 36 cm, G = 0.059 T/cm, R = 13.7 sm• Drift 36 cm• No RF

0 2 4 6 8 10 12 14 16Z (m)

−0.5

0.0

0.5

1.0

1.5

2.0

2.5

β (m

)

Lattice and β−functions of Q−channel(P = 375 MeV/c)

βxβy

Figure 6:

4


Muon test beam –Decay channel

4 Muon Beam Characteristics in Q-Channel

• Radius of aperture 13.7 cm• E-window 255-355 MeV • T-window ±75 cm

0 2 4 6 8 10 12 14 16Z (m)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Transmission and emittance in Q−channel(T−window 75 cm, E−window 255−355 MeV)

π/p (%)µ/p (%)(π+µ/p (%)µ emittance (cm)

Figure 7:

0 2 4 6 8 10 12 14 16Distance (m)

−20

−15

−10

−5

0

5

10

15

20X

(cm

)Trajectories of muons after π−µ−decay

(pions are going along the axis)

Figure 8:

−200 −100 0 100 200Time x c (cm)

100

300

500

700

900

Tot

al e

nerg

y (M

eV)

Longitudinal phase space after decay channelµ/p = 0.5% (total), 0.07% (in the window)

Figure 9:

−15 −10 −5 0 5 10 15X (cm)

−40

−30

−20

−10

0

10

20

30

40

PX (

MeV

/c)

Transverse phase space after decay channelR.m.s. emittance of muon beam 5.9 mm

Figure 10:

5


Ring Cooler ideas

• Initial scheme from V.Balbekov

Injection Extraction

Period

7.5 m

61.1

61.1

316.5 cm

Period:

Solenoid coil

LH absorber

LiH wedge absorber

32.2 deg

- - -

+

+

+

and field flipCavity


Ring Cooler –New scheme from Balbekov

5 Ring Cooler

6.33 m

1.1 m

Liquid hydrogen absorber

201 MHz cavity

LiH wedge absorber

Bending magnet45 deg, R = 30 cm

Direction of magnetic field

Solenoid coils

Figure 11: Schematic of ring cooler


Ring Cooler - Parameters

Ring cooler: list of parameters

1. Circumference 32.4 m2. Kinetic energy of muons 125-164 MeV3. Revolution frequency 8.4 MHz4. Bending radius 30 cm5. Bending field 2.52 T6. Solenoid field ±3.56 T7. RF frequency 201.25 MHz8. Accelerating gradient 15 MeV/m9. RF harmonic number 2410. Main absorber LH, 120 cm11. Wedge absorber LiH, dE/dy = 0.8 MeV/cm12. β-function 42 cm

Necessary conditions:

• Field flip• Ho dispersion at SS

−1.0 −0.5 0.0 0.5 1.0Z (m)

−0.5

−0.4

−0.3

−0.2

−0.1

0.0

0.1

0.2

0.3

0.4

0.5

Dis

pers

ion

(m)

Dispersion function in the ring cooler(instantaneous field flip)

HorizontalVertical

Figure 12:

7


Ring Cooler-Performance

6 Cooling in the Ring

Injected beam: σX = σY = 4.87 cmσPx = σPy = 26 MeV/cσZ = 8.5 cm, σE = 18.8 MeVεX = εY = 1.2 cm, εZ = 1.5 cm

After 15 revolutions: εX = 0.32 cmεY = 0.37 cmεZ = 0.68 cm

Transmission: 68% with decay49% without decay

0 10 20 30 40 50 60Period number (1 rev.=4 per.)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Em

ittan

ce/T

rans

mis

sion

Beam emittance and transmission in the ring cooler

Horizontal emittance (cm)Vertical emittance (cm)Longitudinal emittance (cm)6D emittance (cm

3)

Transmission

Figure 13:

8


Ring Cooler -Performance

7 Phase Space of the Beam

−20 −10 0 10 20X (cm)

−100

−50

0

50

100

PX (

MeV

/c)

Transverse phase space in the ring cooler(0 rev., normalized r.m.s. emittance 12 mm)

Figure 14:

−20 −10 0 10 20X (cm)

−100

−50

0

50

100

PX (

MeV

/c)

Transverse phase space in the ring cooler(15 rev., normalized r.m.s. emittance 3.2 mm)

Figure 15:

−30 −20 −10 0 10 20 30Time x c (cm)

200

250

300

350

400

Tot

al e

nerg

y (M

eV)

Longitudinal phase space in the ring cooler(0 rev., normalized r.m.s. emittance 20 mm)

Figure 16:

−30 −20 −10 0 10 20 30Time x c (cm)

200

250

300

350

400

Tot

al e

nerg

y (M

eV)

Longitudinal phase space in the ring cooler(15 rev., normalized r.m.s. emittance 7.2 mm)

Figure 17:

9



8 Bunching in the Ring (Q-Decay channel)

Nµ = 6 · 1010 × 6 · 10−4 = 3.6 · 107


0.0

0.5

1.0

1.5

2.0

2.5

3.0

Em

ittan

ce/T

rans

mis

sion

Beam emittance and transmission in the ring cooler

εx (cm)εy (cm)εz (cm)ε6 (cm

3)

Tr.x1000

Figure 18:

−20 −10 0 10 20X (cm)

−100

−50

0

50

100

PX (

MeV

/c)

Transverse phase space in the ring cooler

After 3 rev.After 15 rev.

Figure 19:

−30 −20 −10 0 10 20 30Time x c (cm)

200

250

300

350

400

Tot

al e

nerg

y (M

eV)

Longitudinal phase space in the ring cooler


Figure 20:

Q-decay channel is a bottleneck

10



Solenoidal channel B = 3.56 T, R = 15 cm, L = 16 m provides 2.5times more muons at the same window. After the bunching:

Nµ = 6 · 1010 × 1.2 · 10−4 = 7.2 · 107


0.0

1.0

2.0

3.0

4.0

5.0

Em

ittan

ce/T

rans

mis

sion

Beam emittance and transmission in the ring cooler(solenoidal decay channel)

Horizontal emittance (cm)Vertical emittance (cm)Longitudinal emittance (cm)6D emittance (cm

3)

Transmission x 1000

Figure 21:

−20 −10 0 10 20X (cm)

−100

−50

0

50

100

PX (

MeV

/c)

Transverse phase space in the ring cooler(solenoidal decay channel)


Figure 22:

−30 −20 −10 0 10 20 30Time x c (cm)

200

250

300

350

400

Tot

al e

nerg

y (M

eV)

Longitudinal phase space in the ring cooler(solenoidal decay channel)


Figure 23:

11


Injection ideas

• It is difficult to inject beam of either pions or muons into the ring cooler.

• Try injecting protons (8GeV-1-3ns bunch) and hit one of the wedge targets. Simulation of pion production and capture at 90 degrees is being conducted by N.Mokhov

• Muon Collider/Neutrino factory fellow –Z.Usubov will help in simulating this setup in Geant4/DPGeant.

• If we can show that it is possible to capture sufficient number of muons this way, then we need to go into an engineering study that will put the design onto a more realistic basis. This can be followed by cost estimates etc.

• The beauty of this scheme (if it works) is that it would demonstrate cooling (6D) on modules that are used by the regular cooling channel. Reusing the modules turn by turn (20 turns foreseen) would reduce the cost of a cooling demonstration channel by that factor.

mucool experiment- plansagni.phys.iit.edu/~capp/workshops/muinst2000/raja.pdf · 2000. 12. 4. ·...

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