LEMMA(LowEmi+anceMu+Mu-Accelerator)
(July26–August2,2017)
LEMMA:novelapproachtoamuoncollider,basedonproduc9onoflowemi=anceµ+µ-pairsbyusingpositronsontarget
Nucl.Instrum.Meth.A807(2016)[arXiv:1509.04454]
Proposaloftheexperiment:studycri9calaspectsoftheLEMMAconcept
-  degrada9onofthepositronbeamproper9escrossingdifferenttargets
-  measurementofmuonbeamproper9es
FabioAnulli(INFNRome),
onbehalfoftheLEMMAgroup
INFNgroupsfrom:Ferrara,FrascaR,Milano
Bicocca,Padova,Pisa,RomaLaSapienza
CERNH2/H4mee,ng,31stMarch,2017
PhysicsmoRvaRons
• 
• 
ThemuoncolliderrepresentsanintriguingopRonsforlongtermstrategyofHEP.
AlternaRveapproachestothemoststudiedproducRonofmuonbeamsfromπ/Κ
decaysfromprotoninteracRonontargetsshouldbeexplored.
• 
Low-emi+anceµ±beamscouldbeobtainedine+e-→µ+µ-processes,atacenter-ofmassjustabovethreshold,bymeansofa~45GeVpositronbeamimpingingonthe
electronsofatarget.
SeveralcriRcalaspectsmustbeexperimentallyverifiedtovalidatetheapproach(e.g.):
–  opRmizaRonofthetargetfeatures
–  degradaRonofthepositronbeams(inordertorecirculate)
–  efficiencyoftheµ+µ- producRon,andparametersoftheproducedbeams
• 
• 
Theproposedexperimentsincludesseveralmeasurementswithdifferentsetups.
InordertoopRmizethebeamRmetwoconsequentperiodswithdifferentbeam
intensiResareenvisaged:
–  StudyofpositronbeamdegradaRon:1-2daysatlow-intensitybeam(45GeVe+)
–  StudyofmuonproperRes:5-6dayswithhigh-intensitye+beam(precededbya
shortrunwitha~22.5GeVmuonbeamforalignmentandcalibraRon)
Day1&2
Low-IntensitybeamconfiguraRon
•  StudyofpositronbeamdegradaRon,comparingresultswithdifferenttargets,including
crystalsinchannelingregime
•  Measurepositronbeamparametersdownstreamtothetarget
-  positronsenergyspectrumandtransverseemi+ance
-  energydistribuRonofradiatedphotons Experimentalsetup:thesameasPHOTAG/AXIAL(seepresentaRonbyLauraBandiera),with
differenttargetandtarget-holder
OpRmalbeamparameters:
•  ParRcletype:positrons
•  Energy:45GeV;energyspread~1%
•  Beampurity:~99%
High-IntensitybeamconfiguraRon
Day2-7
•  StudyofkinemaRcproperResoftheproducedmuons
•  Measuretheµ+µ-producRonratefortheprovidedpositronbeamfeatures
(momentumandenergyspread)
•  Measuremuonsmomentumandemi+ance(needfulltrackingofmuons)
•  Signaleventstaggedwith2(oppositecharge)tracksinthemuonchamber,and
the“µ-”candidatenotidenRfiedasanelectroninthesamplingcalorimeter.
ing
l
r
samp eter(fo
im
calor aveto)
h
b
Bha
•  Experimentalsetup,modifiedasshowninfigure
e+ (µ+)
SD4
addiRonalSitelescopes
(2x2or10x10cm2)
SD5
deflectedµ-
SD6
deflectede+-beam
SD5
SD6
deflectedµ+
absorber
(concrete
oriron)
largemuondrikchamber
Target:3-6cmthickberillium
(toincreaseproducRonrate)
0.50m
BMfield:1.26T
(needaccuratefieldknowledgeto
preciselymeasuremuonmomentum)
23.787
24.052
24.60
25.60
26.20
Day2-7
High-IntensitybeamconfiguraRon:requests
Beams
•  Becauseoftheverylowe+e-→µ+µ-crosssecRon(~0.4µbfora45GeVe+)weneed
abeamwiththehighestpossibleintensity,andsmallspotsizeandenergyspread:
•  45GeVmomentume+beam;energyspread~1%;beampurity:~99%
•  5x106e+/spill;spotsize:~1cm2orless
UnderthesecondiRonsweexpectabout5event/spillwiththe3cm-thickBetarget
•  Forthealignmentofmuontrackers(SD5&SD6)wewouldneedµ±beamsof~22.5
GeV,forafewhoursatthebeginofthistest
Weneedtoinstallseveralnewdetectors,thatneedhandlingandsupports:
•  SD4(Si-tracker)canbehostedbythesamesupportsthatholdSD2andthetarget
•  ThetwoSD5shouldbeplacedascloseaspossibletotheBMexit,whilethetwoSD6
shouldbeatadistanceof~4-5metersfromtheBMexit.Bothneedasupportortable
•  ThesamplingcalorimeterneedsatableforposiRoning
•  Weneedanironabsorberforstoppingthee+beaminfrontofthemuonchamber
•  ThetwoAXIALcalorimetersmightbemovedupstreamofabout1.5meterstofree
spaceforthenewdetectors
TheBMfieldshouldbeaccuratelymeasuredforaprecisemeasurementofthemuon
momenta:couldthisbeprovided?