M Bonesini Report on Milanosystem INFN TOF M

M. Bonesini Report on Milanosystem INFN TOF M. Bonesini - 29 -03 -06 VC 1

Outline q TOF 0 current design (TP endorsed) q TOF plans for Frascati testbeam q status of redesign of magnetic shielding: TOF-only, TOF+MUCAL M. Bonesini - 29 -03 -06 VC 2

Rates (Singles per ms) target insertion reduced to get 600 good mu+/sec (AUG 05) LAHET Geant 4 MARS Average TOF 0 1722 1762 1508 1664 TOF 1 813 832 712 786 Tracker 1 771 790 675 745 Tracker 2 629 644 551 608 TOF 2 627 641 549 606 Good μ+ (Ev/sec) 621 635 544 600 M. Bonesini - 29 -03 -06 VC 3

Present design of TOF 0 From D. Adams & T. Roberts simulations a 40 x 40 cm 2 active area and a 4 cm segmentation seems a good choice BC-420 scintillator bars 40 x 4 x 2. 5 cm 3 ordered at Bicron (emission peak ~390 nm) some problems with plexiglas procurement for lightguides (it must be UVT, not commercial one) M. Bonesini - 29 -03 -06 VC 4

Prototype delivery Mechanics (see later for details) Cables, electronics, calibration system: n n n RG 213 cables, HV cables, splitters … available in Milano One CAEN V 1290 TDC, one CAEN V 2718 DAQ module available in Milano -> we will start to test prototype with cosmics and a proto-DAQ Laser calibration system: studies are under-way with Pv group to define choice of fibers, … M. Bonesini - 29 -03 -06 VC 5

1. TOF 0 prototype timescale 1. April : counter prototypes construction; tests of laser calibration system 2. May/June: test of prototypes with cosmics + R 4998 PMTs test with laser system 3. July: BTF testbeam M. Bonesini - 29 -03 -06 VC 6

Prototype mechanics • • • TOF 0 counters CAD design ready scintillator delivery (BC 420) by end of March/early April lightguides with REPSOL Glass plexiglas + in-house machining M. Bonesini - 29 -03 -06 VC 7

TOF frond-end electronics 3 choices, in order of difficulty: 1. 2. 3. CF discriminator + TDC Splitter + L. E. discriminator/TDC + QADC ALICE Nino chip (integrator+ fast discriminator) + TDC M. Bonesini - 29 -03 -06 VC 8

Discriminator choice Choice between: 1. 2. 3. CF discrimininator : no need of time-walk correction no QDC line/splitter needed, but st is usually worse L. E. discriminator: st is usually better, but a QDC is needed ALICE NINO chip: it includes a discriminator + an integrator to make possible TOT correction (slightly equivalent to p. h. correction). According to ALICE coll. solution 3 is equivalent to 2 Problem: while solutions 1 -2 are commercial ones (CAEN or …); solution 3 needs some R&D M. Bonesini - 29 -03 -06 VC 9

The BTF testbeam Energy range 25 -750 Me. V e-/e+ Max rep rate 50 Hz Pulse duration 10 ns Current/pulse 1 -1010 particles Testbeam 10+2 days requested for beginning of June -> they will go to July probably We will try to have our DAQ based on CAEN V 2718 (not use default BTF one, Labview based) We can test TOF resolutions, not rate effects (for this we can do only lab tests with our laser system) M. Bonesini - 29 -03 -06 VC 10

What we plan to test in BTF, as regards TOF FEE reference solution (HARP-like): Harp splitter+V 775 TDC + V 792 QADC + L. E. discriminator MICE baseline-1 solution: V 1290 TDC + CF discriminator (Mb-1) MICE baseline-2 solution: Harp splitter + V 1290 TDC + QADC + L. E. discriminator. For the time being QADC will be V 792, waiting for new CAEN QADC based on V 1724, to be delivered end of this year (Mb-2) If available: V 1290 TDC + ALICE NINO chip (discriminator+integrator) M. Bonesini - 29 -03 -06 VC 11

Some considerations for TOFFE MICE baseline-1 solution is easy and if works minimize manpower (our more delicate issue) we can try to adopt Mb-1 to proceed later to Mb-2 (still reduce manpower) ALICE NINO solution requires real work: I will suggest to consider it only if Mb-1 or Mb 2 will not work Real delicate point: choice of CF discriminator M. Bonesini - 29 -03 -06 VC 12

Magnetic shielding re-design all stuff triggered by the fact that Hamatsu has increased the cost of fine-mesh PMTs as respect to previous quotations by 50% !!!! (increase of cost of fine-mesh grids, according to Hamamatsu) and conventional PMTs used for TOF 0 R 4998 are better (smaller TTS, rate capability, …) studies by J. Cobb+ H. Witte to see if we can change B// (not shieldable in conventional PMTs) into B_|_ (shieldable) M. Bonesini - 29 -03 -06 VC 13

TOF 1 or 2 PMT geometry Most of the following is just paste&cut from John&Holger notes/studies credits&questions to them M. Bonesini - 29 -03 -06 VC 14

B field components at TOF 2: no iron shield From John&Holger 2 -D computations M. Bonesini - 29 -03 -06 VC 15

B field at TOF 2: one 100 mm iron shield (current design) M. Bonesini - 29 -03 -06 VC 16

B field is ~ 200 G //; ~ 0. 1 T _|_ M. Bonesini - 29 -03 -06 VC 17

B field at TOF 2 with 2 iron shields sandwiching TOF 2 (100 mm gap) M. Bonesini - 29 -03 -06 VC 18

• B// ~ 40 Gauss, B_|_ ~ 0. 13 T • Problem: individual PMTs must be shielded with soft iron, but this implies a 3 -D calculation to be completely sure • Valuable option to be finalized (conventional PMTs cheaper + better performances) M. Bonesini - 29 -03 -06 VC 19

Additional complications 100 mm gap is small for TOF 2 (or TOF 1) mechanical mounting (supports, …) -> enlarge gap to 120 mm MUCAL is just wondering about is own PMTs … and asking why not to put the 1 st KLOE module just behind TOF 2 … -> see what happens enlarging the gap M. Bonesini - 29 -03 -06 VC 20

B-field for different gaps Br M. Bonesini - 29 -03 -06 VC 21

M. Bonesini - 29 -03 -06 VC 22

Scanning the 200 mm gap M. Bonesini - 29 -03 -06 VC 23

M. Bonesini - 29 -03 -06 VC 24

Conclusions up to now for TOF 0 prototypes we are in schedule for BTF testbeam re-design of magn shieldings under study n n Option for TOF 1 or TOF 2 only (100, 120 mm gap) seems ok; needs only cross-check with 3 -D computations for mild-iron single PMT shieldings and clearly a re-design of lightguides for TOF 1/TOF 2 (longer lightguides) Option for TOF 2+1 st KLOE layer (200 – 240 mm gap) needs major re-design of shields (outer radius, thickness …) Br is too big and fiels have not smooth behaviours M. Bonesini - 29 -03 -06 VC 25