Pion Production Capture M Yoshida Osaka Univ COMETMu

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Pion Production / Capture M. Yoshida (Osaka Univ. ) COMET/Mu 2 e Joint Workshop

Pion Production / Capture M. Yoshida (Osaka Univ. ) COMET/Mu 2 e Joint Workshop Jan. 23, 2009, LBNL

Pions at Target n n MARS simulation Count pions at target surface Compare momentum

Pions at Target n n MARS simulation Count pions at target surface Compare momentum distribution for Tungsten, Gold, Copper and Graphite Heavy material has softer distributions R (mm) L (mm) Backward (pions/proton) (P<0. 5 Ge. V/c) Forward (P<1. 5 Ge. V/c) W 6 160 0. 113 0. 819 Au 6 160 0. 112 0. 814 Cu 6 240 0. 101 0. 799 Graphite 20 600 0. 081 0. 653 Forward Backward

Pion Production in MARS/QGSP n n Compare pion yields in tungsten for MARS and

Pion Production in MARS/QGSP n n Compare pion yields in tungsten for MARS and QGSP_BIC # of backward pions in MARS is half of that in QGSP_BIC Backward pi- / proton MARS Forward 0. 11 0. 15 (P<500 Me. V/c) QGSP_BIC 0. 22 0. 41 (P<500 Me. V/c) Backward pions QGSP_BIC MARS Forward pions QGSP_BIC MARS

Pion capture solenoid n Simple as consisting of 4 coils ¨ n Inner bore

Pion capture solenoid n Simple as consisting of 4 coils ¨ n Inner bore diameter is 1 m - 1. 34 m Capture low-energy pions in 5 T solenoid field Collect backward pions ¨ Energy deposit on superconducting coil of capture solenoid should be << 100 W ¨ Thin solenoid coil of Al-stabilized SC to reduce cold mass ¨ Thick radiation shield surrounding target ¨ n Matching to subsequent transport solenoid Gradient from 5 T to 2 T ¨ Inject proton beam at coil gap ¨ n Tilt target by 10 deg.

Pion Capture Solenoid System 1140 k. AT 1200 1400 1000 300 600 1220 To

Pion Capture Solenoid System 1140 k. AT 1200 1400 1000 300 600 1220 To transport solenoid 1340 300 954 k. AT 1908 k. AT 6720 k. AT

Radiation on capture coil 0. 6 MGy/8 x 1020 protons n SC coil 4

Radiation on capture coil 0. 6 MGy/8 x 1020 protons n SC coil 4 g/cm 3 Density ¨ Thickness 60 mm (50 cm<R<56 cm) ¨ n Heat load 30 cm-thick tungsten shield inserted ¨ 2 x 10 -5 W/g for 8 Ge. V x 7 micro. A ¨ 10 W on coil ¨ n Radiation dose ¨ 0. 6 MGy for 8 x 1020 protons 10 W 30 cm 7 k. W Graphite: 2 k. W Tungsten: 3 k. W

Target geometry n Production and transport in MARS simulation down to 3 m from

Target geometry n Production and transport in MARS simulation down to 3 m from target

Target position B@target=3. 75 T B@target=5 T n n Generate pions by MARS, 500

Target position [email protected]=3. 75 T [email protected]=5 T n n Generate pions by MARS, 500 k protons Tracking to 17 m downstream from target in G 4 Beamline Straight transport solenoid 22% more muon yield at Dz=250 mm ¨ Need to estimate radiation on coil n n Cooling Radiation damage Large bore 4. 99 T 5 T 4. 8 T 4. 9 T 4. 5 T 3. 75 T Target will be shifted by Dz=250 mm in the following studies Target position Dz (mm)

Tracking in MARS / G 4 Beamline n n n So far, Pions are

Tracking in MARS / G 4 Beamline n n n So far, Pions are generated and transported in MARS to 3 m downstream, and input them to G 4 Beamline Difference in muon momentum distribution In the following studies, generate particles by MARS, transport by G 4 Beamline.

Yields at z=3 m Count pions and muons at z=3 meter in R<180 cm

Yields at z=3 m Count pions and muons at z=3 meter in R<180 cm n Muon fraction at 3 m downstream from target = 45% (MARS) n MARS pion 0. 0194 muon 0. 0234 QGSP_BIC pion 0. 0436 muon 0. 0473

Time spectrum at z=3 m n n n MARS production + G 4 Beamline

Time spectrum at z=3 m n n n MARS production + G 4 Beamline tracking Distributions at z=3 m from target Long tale ¨ 0. 0027/0. 043=6% MARS pion muon 6% in 100 ns-200 ns time (ns)

Muons at z=17 m n n n MARS production + G 4 Beamline transport

Muons at z=17 m n n n MARS production + G 4 Beamline transport Transport in straight solenoid 17 m down to stopping target incoming muons ¨ n momentum (Me. V/c) Stopping muons ¨ n 0. 032 muons/proton all muons stopping muons 0. 0034 muons/proton Many muons arrive in measurement time window ¨ need to optimize transport solenoid to select muons time (ns)

Summary n Pion yield in various material ¨ n Pion production in MARS and

Summary n Pion yield in various material ¨ n Pion production in MARS and QGSP_BIC is compared ¨ n n n Tungsten/Gold yield MARS yield half in backward pions Investigating tracking in MARS and G 4 Beamline MARS production + G 4 Beamline tracking produce 0. 043 p-+m- (0. 019 m-) / proton at entrance of transport solenoid (z=3 m) Long tale in arrival time distributions at stopping target ¨ need to optimize transport solenoid