Very low Emi,ance Muon Beam using positron beam on target M. Antonelli (INFN-­‐LNF) Chicago (USA), ICHEP 2016 References: •  M.Antonelli, E.Bagli, M.Biagini, M.Boscolo, G.Cavoto, P.Raimondi and A.Variola, “Very Low Emi-ance Muon Beam using Positron Beam on Target”, IPAC (2016) •  M. Antonelli, “Performance es;mate of a FCC-­‐ee-­‐based muon collider”, FCC-­‐WEEK 2016 •  M. Antonelli, “Low-­‐emi-ance muon collider from positrons on target”, FCC-­‐WEEK 2016 •  M. Antonelli, M. Boscolo, R. Di Nardo, P. Raimondi, “Novel proposal for a low emi-ance muon beam using positron beam on target”, NIM A 807 101-­‐107 (2016) •  P. Raimondi, “Exploring the poten;al for a Low Emi-ance Muon Collider”, in Discussion of the scienLfic potenLal of muon beams workshop, CERN, Nov. 18th 2015 •  M. Antonelli, PresentaLon Snowmass 2013, Minneapolis (USA) July 2013, [M. Antonelli and P. Raimondi, Snowmass Report (2013) also INFN-­‐13-­‐22/LNF Note Also inveSgated SLAC team: L. Keller, J. P. Delahaye, T. Markiewicz, U. Wienands: o  “Luminosity Es;mate in a Mul;-­‐TeV Muon Collider using e+e-­‐à µ+µ-­‐ as the Muon Source”, MAP 2014 Spring workshop, Fermilab (USA) May ’14 o  Advanced Accelerator Concepts Workshop, San Jose (USA), July ‘14 Involved persons: • 
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M. Antonelli, M. Biagini, M. Boscolo, S Dabagov, M. Dreucci, A. Ghigo, S. Guiducci, L. Pellegrino, M. Rotondo, T. Spadaro, A. Stella, A.Variola (INFN-­‐LNF) F.Bedeschi, F. Cervelli, R.Tenchini (INFN-­‐Pi), G.Tonelli (Univ.& INFN-­‐Pi) U. Dosselli, M. Morandin, G. Simi (INFN-­‐Pd) , D. Lucchesi, A. Wulzer, M. Zanea (Univ.& INFN-­‐Pd) F. Anulli, G. Cavoto (INFN-­‐Roma1) M. CenSni, A.Mostacci, L. Palumbo (Uni-­‐Sapienza & INFN-­‐Roma1) E.Bagli, V. Guidi, A. Mazzolari (INFN-­‐Fe) M. Prest (Uni-­‐Insubria&INFN) P.Raimondi (ESRF) J. P. Delahaye, P. Sievers, R. Di Nardo (CERN) I.Chaikovska, R. Chehab (LAL-­‐Orsay) L. Keller, T. Markiewicz (SLAC) Idea for low emicance µ beam ConvenSonal producSon: from proton on target π, K decays from proton on target have typical Pµ~ 100 MeV/c (π, K rest frame)
whatever is the boost PT will stay in Lab frame à very high emi,ance at producSon point à cooling needed! Direct µ pair producSon: Muons produced from e+e-­‐à µ+µ-­‐ at √s around the µ+µ-­‐ threshold (√s~0.212GeV) in asymmetric collisions (to collect µ+ and µ-­‐ ) Advantages: 1.  Low emi,ance possible: Pµ is tunable with √s in e+e-­‐àµ+µ-­‐ Pµ
can be very small close to the µ+µ-­‐ threshold 2.  Low background: Luminosity at low emicance will allow low background and low ν radiaSon (easier experimental condiSons, can go up in energy) 3.  Reduced losses from decay: muons can be produced with a relaSvely high boost in asymmetric collisions 4.  Energy spread: Muon Energy spread also small at threshold, it gets larger as √s increases, one can use correlaSon with emission angle (eventually it can be reduced with short bunches) Disadvantages: •  Rate: much smaller cross secSon wrt protons σ(e+eàµ+µ-­‐) ~ 1 µb at most i.e. Luminosity(e+e-­‐)= 1040 cm-­‐2 s-­‐1 à gives µ rates 1010 Hz Possible Schemes •  Low energy collider with e+/e-­‐ beam (e+ in the GeV range): 1.  ConvenSonal asymmetric collisions (but required luminosity is beyond current knowledge) 2.  Positron beam interacSng with conSnuous beam from electron cooling (too low electron density, 1020 electrons/cm-­‐3 needed to obtain an reasonable conversion efficiency to muons) •  Electrons at rest (seems more feasible): 3. 
4. 
– 
– 
e+ on Plasma target e+ on standard target Need Positrons of ~45 GeV γ(µ)~200 and µ laboratory lifeSme of about 500 µs e+ beam target Beam with e+ and µ+µ-­‐ Ideally muons will copy the positron beam Muons angle contribuSon to µ beam emicance The target thickness and c.o.m. energy completely determine the emicance contribuSons due to muon producSon angle X= L X’ +/-­‐ X’max sin
µ
x 10
e+ µ
L -2
0.5
0.45
θµmax=4 me (s/4-­‐mµ2)1/2/s εµ = x x’max /12= L (θµmax)2/12 0.4
0.35
X’ X’max 0.3
0.25
L X’max 0.2
0.15
1 mrad 0.1
0.05
0
0.21
0.215
[Babayaga 3.5] 0.22
0.225
0.23
s (GeV)
X Criteria for target design •  Number of µ+µ-­‐ pairs produced per interacLon: n(µ+µ-­‐)= n+ ρ-­‐ L σ(µ+µ-­‐) n+ = number of e+ ρ-­‐ = target electron density L = target length •  ρ-­‐ L costraints –  Ideal target (e-­‐ dominated) (ρ-­‐ L)max=1/σ(radiaSve bhabha) ≈ 10 25 cm-­‐2 (beam lifeSme determined by radiaSve Bhabha) –  With (ρ-­‐ L)max one has a maximal µ+µ-­‐ producSon efficiency ~10-­‐5 –  Muon beam emicance increases with L (in absence of intrinsic focusing effects) è increase ρ-­‐ –  ConvenSonal target (ρ-­‐ L)max depends on material (see next slides) Criteria for target design Bremsstrahlung on nuclei and mulSple scacering (MS) are the dominant effects in real life… Xo and electron density will macer: •  Heavy materials –  minimize emicance (enters linearly) è Copper has about same contribuSons to emicance from MS and µ+µ-­‐ producSon –  high e+ loss (Bremsstrahlung is dominant) •  Very light materials –  maximize producSon efficiency(enters quad) è H2 –  even for liquid need O(1m) target è emicance increase •  Not too heavy materials(Be, C ) –  Allow low emicance with small e+ loss opLmal: not too heavy and thin ApplicaSon for MulS-­‐TeV Muon Collider as an example •  Use thin target with high efficiency and small e+ loss •  Positrons in storage ring with high momentum acceptance •  No need of extreme beam energy spread Possible target: 3 mm Be 45 GeV e+ impinging beam •  Emicance at Eµ = 22 GeV: Muons at the target exit surface εx = 0.19 ⋅10-9 m-­‐rad MulLple Sca,ering contribuLon is negligible -­‐> µ arer producSon is not affected by nuclei in target -­‐> e+ beam emicance is preserved, not being affected by nuclei in target (see also next slide) •  Conversion efficiency: 10−7 •  Muons beam energy spread: 9% [Geant4] ~1 mm diamond target works with similar performances (more resistant to PEDD) Positrons Storage Ring Requirements •  Transverse phase space almost not affected by target •  Most of positrons experience a small energy deviaSon: A large fracSon of e+ can be stored (depending on the momentum acceptance) –  10% momentum acceptance will increase the effecSve muon conversion efficiency (produced muon pairs/produced positrons) by factor 100 3 mm Berillium Positrons at the target exit surface [Geant4] [Geant4] SchemaSc Layout for muon source from e+ e+ injector Circumference 6 km ρ 0.6 km number e+ bunches 100 e+ bunch spacing 200 ns Beam current 240 mA e+ ParScles/bunch 3 ·∙ 1011 Rate e+ on target 1.5 ·∙ 1018 e+/s U0 0.58 GeV Ptot 139 MW B 0.245 T Positron ring µ+ target µ+ accumulator µ-­‐ accumulator e+ µ-­‐ Key point: Positron source requirements strictly related to the e+ ring momentum acceptance To acceleraSng complex 60 m isochronous rings recombine bunches for ~ 1 τµlab ~2500 turns Muon beam parameters Assuming •  a positron ring with a total 25% momentum acceptance •  ~3 × FCC-­‐he positron source rate •  push on mom. acceptance and e+ source performances •  improve target performances Very small emi,ance, high muon rates but relaSvely small bunch populaSon: Ø  The actual number of µ/bunch in the muon collider can be larger by a factor ~ τµlab(HE)/500 µs (~100 @6 TeV) by topping up. Low Emicance Muon Muon Accelerator Drar Parameters comparable luminosity with lower Nµ/bunch (lower background) thanks to very small emicance (and lower beta*) Of course, a design study is needed to have a reliable esSmate of performances "
Parameter"
LUMINOSITY/IP"
Beam Energy"
Hourglass reduction factor"
Muon mass"
Lifetime @ prod"
Lifetime"
c*tau @ prod"
c*tau"
1/tau"
Circumference"
Bending Field"
Bending radius"
Magnetic rigidity"
Gamma Lorentz factor"
N turns before decay"
βx @ IP"
βy @ IP"
Beta ratio"
Coupling (full current)"
Normalised Emittance x "
Emittance x "
Emittance y "
Emittance ratio"
"
Units"
cm-2 s-1"
GeV"
"
GeV"
sec"
sec"
m"
m"
Hz"
m"
T"
m"
T m"
"
"
m"
m"
"
%"
m"
m"
m"
"
LEMC-6TeV"
"
5.09E+34"
3000"
1.000"
0.10566"
2.20E-06"
0.06"
658.00"
1.87E+07"
1.60E+01"
6000"
15"
667"
10000"
28392.96"
3113.76"
0.0002"
0.0002"
1.0"
100"
4.00E-08"
1.41E-12"
1.41E-12"
1.0"
Bunch length (zero current)"
mm"
0.1"
Bunch length (full current)"
mm"
0.1"
mA"
Hz"
s"
#"
#"
#"
micron"
micron"
rad"
rad"
0.048"
5.00E+04"
2.00E-05"
1"
6.00E+09"
1.00"
1.68E-02"
1.68E-02"
8.39E-05"
8.39E-05"
Beam current"
Revolution frequency"
Revolution period"
Number of bunches"
N. Particle/bunch"
Number of IP"
σx @ IP"
σy @ IP"
σx' @ IP"
σy' @ IP"
Annual dose p on target 1 mS/year e+ on target muon rate: p on target opSon 3 1013 µ/s e+ on target opSon 9 1010 µ/s Muon collider reach: an example •  Study the same benchmark used for White Paper: –  New heavy parScles, both colored and EW charged (~vector like quarks)è xsec can be predicted –  FCC reach stops at MX = 7 TeV •  Hadron machine pays the price of the exponenSally falling PDF è mulS-­‐TeV muon machine can be compeSSve! 16 Muon Collider: SchemaSc Layout for positron based muon source Neutrino)Factory)(NuMAX))
Front(End( (((Cool?( (((Accelera1on(
ing(
0.2–1(
GeV(
Ini1al(Cooling(
1–5(
GeV(
#−!
Final(Cooling(
6D(Cooling(
#+!
#−!
Key
~1011 µ / sec from e+e-gµ+µChallenges
Key
1015 e+/sec, 100 kW class target, NON
distructive process in e+ ring
R&D
ν Factory Goal:
1021 µ+ & µ− per year
within the accelerator
acceptance
ν
(((Accelera1on(
Bunch(
Merge(
µ-­‐ ν
5(GeV(
(((Cooling(
Charge(Separator(
Capture(Sol.(
Decay(Channel(
isochronous rings Buncher(
Phase(Rotator(
µ
Ini1al(Cooling(
Front(End(
+ 100 KMW?Class(Target(
W target e+ ring Combiner(
SC(Linac(
LHeC-­‐class e+ source & e+ acceleraSon at Accumulator(
45 GeV (circular/linear Buncher(
opSons) (((Proton(Driver(
#+!
Accelerators:(
Single?Pass(Linacs((
(
Share same complex
Muon)Collider)
Positron Beam (((! Storage(Ring(
(281m(
6D(Cooling(
MW?Class(Target(
Capture(Sol.(
Decay(Channel(
Buncher(
Phase(Rotator(
Buncher(
Accumulator(
SC(Linac(
(((Proton(Driver(
µ?Collider Goals:
126 GeV !
~14,000 Higgs/yr
Multi-TeV !
Lumi > 1034cm-2s-1
(((Collider(Ring(
ECoM:(
(
Higgs(Factory(
to(
~10(TeV(
Accelerators:(((((
Linacs,(RLA(or(FFAG,(RCS(
#+!
#−!
Neutrino)Factory)(NuMAX))
Front(End( (((Cool?( (((Accelera1on(
ing(
Key
~1013-1014 µ / sec
Challenges
Share same
complex
Tertiary
particle pgπgµ:
Bunch(
Merge(
#−!
6D(Cooling(
6D(Cooling(
Charge(Separator(
Cost eff.νlow RF SC
Detector/
Fast pulsed magnetµ?Collider
machine
Goals:
(281m(
126
GeV
!
(1kHz)
interface
~14,000 Higgs/yr
#−!
Multi-TeV !
Fast acceleration Lumi >
1034cm-2s-1
Background
mitigating µ decay
by µ decay
#+!
1–5(
GeV(
Accelerators:(
Single?Pass(Linacs((
(
(((Collider(Ring(
ν Factory Goal:
1021 µ+ & µ− per
ECoMyear
:(
(
within the accelerator
Higgs(Factory(
acceptance
to(
~10(TeV(
ν
5(GeV(
#−!
ν
µ?Collider#Goals:
+!
#−!
(281m(
Accelerators:(((((
126 GeV !
Linacs,(RLA(or(FFAG,(RCS( ~14,000 Higgs/yr
Multi-TeV !
Lumi > 1034cm-2s-1
share the same complex (((Accelera1on(
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#−!
6D(Cooling(
#+!
6D(Cooling(
µ-­‐ ν
5(GeV(
(((! Storage(Ring(
(((Cooling(
Charge(Separator(
Capture(Sol.(
Decay(Channel(
isochronous rings Buncher(
Phase(Rotator(
µ
Ini1al(Cooling(
Front(End(
+ 100 KMW?Class(Target(
W target Combiner(
SC(Linac(
FCC-­‐he-­‐class e+ source & e+ acceleraSon at Accumulator(
45 GeV (circular/linear Buncher(
opSons) (((Proton(Driver(
e+ ring Share same complex
0.2–1(
GeV(
ν Factory Goal:
1021 µ+ & µ− per year
within the accelerator
acceptance
(((Accelera1on(
(((Cooling(
MW?Class(Target(
MW?Class(Target(
Capture(Sol.(
Capture(Sol.(
Decay(Channel(
Decay(Channel(
Buncher(
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Phase(Rotator(
Phase(Rotator(
Ini1al(Cooling(
Ini1al(Cooling(
Combiner(
Buncher(
Buncher(
Accumulator(
Accumulator(
SC(Linac(
SC(Linac(
Accelerators:(
Single?Pass(Linacs((
Fast
cooling
(
(τ=2µs) by 106 (6D)
Front(End( (((Cool?( (((Accelera1on(
#+!
ing(
Muon)Collider)
Positron Beam #+!
Ionization
cooling
0.2–1(
1–5(
GeV(
GeV(
High field solenoids (30T)
High Temp Superconductor
Muon)Collider)
Neutrino)Factory)(NuMAX))
(((Proton(Driver(
Front(End(
(((Proton(Driver(
(((! Storage(Ring(
Final(Cooling(
Buncher(
MW?Class(Target(
Capture(Sol.(
Decay(Channel(
Buncher(
Phase(Rotator(
MW proton driver
MW class target
NCRF in magnetic field
Accumulator(
SC(Linac(
Key
R&D
Ini1al(Cooling(
(((Proton(Driver(
Key
~1011 µ / sec from e+e-gµ+µChallenges
Key
1015 e+/sec, 100 kW class target, NON
distructive process in e+ ring
R&D
(((Collider(Ring(
ECoM:(
(
Higgs(Factory(
to(
~10(TeV(
Accelerators:(((((
Linacs,(RLA(or(FFAG,(RCS(
#+!
#−!
Key Feasibility Issues Positron Source HIGH rate Muon Target Non destrucLve Positron Ring Mom. acceptance NEED deep invesSgaSon (design study) Targets survival • 
• 
• 
• 
µ AcceleraSon Collider Ring Collider MDI Collider Detector (mostly) independent on muon source Benefit from MAP studies First OpScs for e+ ring 43.8 GeV e+ 4.1 mm Si Target Channeling plane: (110) [Geant4] [Geant4] Going to lighter targets for µ producSon Look to light liquid targets to reduce problems of thermo-­‐mechanical stresses LLi might be a good opSon: <factor 4 ε increase è
<2 worse In L 25% gain in e+ survival @ same µ producSon efficiency Proposed/tested for targets for n producSon High Boiling point 1615 K Mass evaporaSon? Safety? Embedded positron source? Positron source extending the target complex? Possibility to use the γ’s from the µ producSon target to produce e+ e+ 45 GeV Thin light target (eventually crystal in channeling) γ’s Dipole magnet e+ e-­‐ pairs Thick heavy target Proposed for example for CLIC Produce a fracSon of 8% e+ of the incoming positron beam W [Geant4] 3 mm Be [Geant4] γ’s angular distribuSon at the target exit Assuming a 10% collecSon efficiency Need to have 45 GeV e+ loss on thin target <1% Fast acceleraSon to 45 GeV (~ KHz) like µ
Target/s survival 100 KW (on the thin one)on small area Embedded positron source? e+ 45 GeV Thin light target (eventually crystal in channeling) γ’s Dipole magnet Thick heavy target e+ injector CollecSon system? Fast acceleraSon: Linac ERL booster Positron ring µ+ e+ µ-­‐ Tests with e+ beam Use terSary 45 GeV e+ beam in CERN North area (H4) (ask for 2 weeks of beam Sme for next year) •  Low intensity (one by one e+ tracking) with crystals and amorphous targets: measure beam degradaSon (emicance energy spectrum) measure produced photons flux and spectrum •  High intensity (up to 5 x 106 /spill) with amorphous targets: measure muon producSon rate and muons kineamaSc properSes Conclusion •  Very low emicance muon beams can be obtained by means of positron beam on target •  High Luminosity at MulS-­‐TeV with much reduced radiological risks •  Some synergy with future e+e-­‐ collider parameters: beam energy, emicance, bunch structure.. But •  CompeSSve muon rates require: –  Challenging positron source (FCC-­‐eh like) –  Positron ring with high momentum acceptance (synergy with next generaSon SR sources) •  Design study and tests to address Key issues LEMC 45 1700 240 ~0.4 >0.1,>100 >>1s Next slides Channeling of produced muons crystal 43.8 GeV e+ 4.1 mm Si Target Channeling plane: (110) amorphous [Geant4] [Geant4]