Detector for the PRISM: PRIME - PRI SM M uon to E lectron conversion - Akira SATO Department of Physics, Osaka University The Project-X Muon Workshop November 8th (Monday), 2010, FNAL
PRIME: from stopping targets to detectors • Thin Stopping Targets • due to mono-energetic muons • Graded Field at Muon Target Solenoid • To maximize transmission efficiency of the curved solenoid. • Curved Solenoid • To suppress low momentum electrons. • Low Mass Tracker • to be transparent to γ ’s. • f < 1 MHz • Electron Calorimeter • Trigger • Cosmic Muon suppression • f < 1 MHz • No Time Window • pure muon beam • + curved solenoid
Introduction • The parameters of muon beam for the Muon beam param. in this study PRISM would have many advantages. Muon intensity 2x10 12 µ/sec • ex). Thinner stopping target to get better electron energy Mean momentum 68 MeV resolution. Momentum spread 3 % Rep. rate 1000 Hz • but also would make a very high instantaneous detector hit rate R inst . Pulse width 100 nsec • Rough estimation Beam size (H.) ~100 mm • R inst Beam size (V.) ~80 mm • = 2x10 12 µ/s / 10 3 pulse/s / 10 -6 /s • =~10 15 Hz • Detector cannot work! will be changed to 40MeV/c +- 3% • We use a Spiral Solenoid Spectrometer to suppress the instantaneous rate. This talk shows a MC study for the stopping target and the spectrometer.
References of this talk PRISM Tech. note PRIME-LoI to J-PARC by N.Sasao !"#$%& !'&()'#* !"(+,$'-(,($ .'$ % /01!2 ! 3( 4')5($6#') 78"($#-(),9 :9 !%6%' ;("%$,-(), '. /<=6#+6> ?=',' @)#5($6#,=> ?=',' ABA> C%"%) A Letter of Intent to D+,'E($ FG> FBBH The J-PARC 50-GeV Proton Synchrotron Experiment ! "#$%&'()$*&# !" #$%& "'#() ! *+'*'&( #' (,*-'. / &*%+/- &'-("'%0 &*(1#+',(#(+ 2'+ / 34!56 ! 7( 1'"8(+&%'" (9*(+%,("#: !" #$%& (9*(+%,("#) ;( $'*( #' +(/1$ <+/"1$%"= +/#%' &("&%#%8%#. /& -'; /& >? ! !" ;%#$ / 34!56 ,@'" <(/,: A$( 34!56 <(/, %& / "(;-.70(&%="(0 -';7("(+=. *@-&(0 An Experimental Search for the µ − − e − <(/,B %#& +(-(8/"# */+/,(#(+& /+( -%&#(0 %" A/<-( >: A$(+( /+( ,/". /08/"#/=(& %" #$( 34!56 <(/,) /,'"= ;$%1$ /+( %"#("&%#.) ,'"'1$+',/#%&%#.) /"0 *@+%#.: C';(8(+) #$(+( Conversion Process at an Ultimate Sensitivity of %& /-&' / 1(+#/%" 0%&/08/"#/=() "/,(-. / 8(+. -'; 0@#. 2/1#'+: A$@& /". 0(#(1#'+ ;$%1$ the Order of 10 − 18 with PRISM @&(& #$( 34!56 <(/, ,@&# <( /<-( #' $/"0-( / 8(+. $%=$ %"&#/"#/"('@& +/#(: !" / ! 7( 1'"8(+&%'" (9*(+%,("#) #/D%"= / #.*%1/- ,@'" -%2( #%,( %" / &#'**%"= #/+=(# #' <( ! > ! &(1) %"&#/"#/"('@& 0(1/. +/#( /,'@"#& #' /" '+0(+ '2 ! >? !# CE F>? !$ ! G&(1 " >? $ *@-&(G&(1 " >? ! # &(1H: A$%& "@,<(+ &$'@-0 <( 1',*/+(0 ;%#$ ! >? !! CE F>? !! ! G&(1 " >? # *@-&(G&(1 " >? ! # &(1H %" #$( 6IJK (9*(+%,("#) ;$%1$ ;%-- <( 1/++%(0 '@# .(/+ ! L??M /# NOP /%,%"= The PRIME Working Group /# #$( <+/"1$%"= +/#%' &("&%#%8%#. 0';" #' >? ! !# : QC'; #' $/"0-( #$%& %"&#/"#/"('@& +/#(RS A$( ,/%" *@+*'&( '2 #$%& "'#( %& #' /"&;(+ #$%& T@(&#%'" ;%#$ / &*%+/- &'-("'%0 &*(1#+',(#(+: A$( "'#( %& '+=/"%E(0 /& 2'--';&B %" #$( "(9# January 1, 2003 &(1#%'") #$( </&%1 *+%"1%*-( %& (9*-/%"(0: U-#$'@=$ 1$/+=(0 */+#%1-( 0."/,%1& %" / ,/="(#%1 V (-0 %& ;(-- D"';") #$%& #.*( '2 &*(1#+',(#(+ %& "(; %" $%=$ ("(+=. *$.&%1& (9*(+%,("#&: A/<-( >W 34!56 <(/, 1$/+/1#(+%&#%1&: 3/+/,(#(+& X/-@(& Y"%#& >? !$ !"#("&%#. ! G&(1 6(/" ("(+=. L? 6(X I"(+=. &*+(/0 # Z [ 4(*(#%#%'" +/#( >?? *** 3@-&( ;%0#$ ! >?? "&(1 N(/, &%E( F$'+%E'"#/-H ! >?? ,, N(/, &%E( F8(+#%1/-H ! \? ,, > http://www-ps.kek.jp/jhf-np/LOIlist/pdf/L25.pdf
Layout and Magnetic Field in This Study • 540 deg. spiral solenoid for the electron spectrometer. • cf. COMET has a 180 deg solenoid for the spectrometer. Spiral Solenoid Spectrometer for PRISM Magnetic Field Configuration S IDE V IEW 7 1 m Calorimeter Track Chamber 6 1 m Solenoid Field Strength [T] Solenoid Field Strength [T] 5 Target 4 3 2 T OP V IEW Curved Solenoid Target Section Target 1 Detector Section Section Iron Shield 0 Spiral 20 22 24 26 -2 0 2 4 6 8 10 12 14 Solenoid Path Length [m] Detector Section
Muon Stopping Targets for the narrow energy spread muon beam
Muon Stopping Target: σ range =38µm p µ = 68MeV/ c ± 3% It is dominated by momentum distribution. &!!! Ti target of 1mm is enough to stop muons. %!! If the performance of phase rotation at PRISM gets better, there is still a room to get a muon-stopping target thinner by a factor of two at most (to about $!! 500 µm full width). #!! p µ [GeV/c] "!! ! 0 0.2 0.4 0.6 0.8 1.0 ! !'& !'" !'( !'# !') !'$ !'* !'% !'+ & !"#$%&'#&(' Range in Ti [mm] Range in Ti [mm]
Parameters of Stopping Targets In the following studies, PRISM cf.COMET Number of layers 20 17 Disk thickness 50µm 200µm Disk diameter 5cm 10cm Disk spacing 5cm 5cm Material Ti Al
Energy Loss of Outgoing Electrons ��������������������������������������� ������������������������� ������������������������������������������������������� ������������������������������������������� ������������������������������������� ���������� ���������������������������������������������������� ��� ��� ��� �������������������������� ��� ����������� ��� 20.7% ��� escaping from the upstream exit ��� ������ ������ 7keV ��� ��� ��� 79.3% ��� ��� � � 0 10 20 30 40 50 � ���� ���� ���� ���� ���� 0 100 200 300 400 500 ������� � ������ ������ ������ ������ ������ Traversed target thickness [µm] Energy loss in the stopping targets ����������������� ������������� [keV] 20 layers of 50µm Ti disks (D=5cm, 5cm separation)
cf. Energy Loss of Outgoing Electrons for COMET ID 200 from COMET-CDR Entries 14874 4000 104. 2 Mean RMS 0.7730 3500 3000 2500 2000 700keV 1500 1000 500 0 108 106 98 100 102 104 p e (MeV/ c ) Figure 6.6: Momentum distribution of µ − − e − conversion signal electrons, including the e ff ect of energy loss in the muon-stopping target. 17 layers of 200µmTi disks (D=10cm, 5cm separation)
Tracking Detector • Main detector to measure Ee • Thickness should be about 0.01 radiation-length to suppress γ backgrounds. • Spatial resolution < 0.5 mm • Hit multiplicity ~ 1 per plane per event • Straw tube tracker • 5mm Φ , 208 tubes per sub-layer • four layers per station • anode readout (X, X’, Y, Y’) • five stations, 48 cm apart A Prototype chamber tested by beam. Anode position resolution of 112 µm.
Track Fitting Simulation hfmomdif hfmomdif Momentum(Fit-True) Entries 126083 Entries 126083 • 5 x-y Tracking Stations Mean -0.04918 Mean -0.04918 RMS RMS 0.1531 0.1531 4 10 • 1-T uniform B 3 • 480 mm spacing 10 • Polyimide:160µm t per plane 2 10 • Multiple Scattering by Break Point Method 10 σ [tracking] = 150 keV/c • Require single hit for each plane 1 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 p fit - p true • σ [tracking] = 150 keV/c hfmomdio_norm hfmomdio_norm Electron Momentum COMET Entries 115967 Entries 115967 • Momentum resolution Counts per 0.05 MeV/c Mean Mean 103.3 103.3 1 RMS RMS 0.2285 0.2285 run time: 2 x 10 7 sec • COMET: rms[total] = 770 keV/c 0.8 • the energy loss uncertainly in the 0.6 muon-stopping target is large. 0.4 BR=10 -16 • PRISM: rms[total] ⇒ 150 keV/c 0.2 0 103 103.5 104 104.5 105 105.5 106 Momentum (MeV/c)
Spiral Solenoid Spectrometer
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