# Presentation: 078064

## Time of Flight System for the MICE Experiment

- Steve Kahn and Kevin Lee
- For the Padova-Milano Group
- A. Guglielmi et al.

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## Legal Statement

- Most of this material has been plagiarized from
- “TOF in Mice” by A. Guglielmi at 13 Jun 2002 detector meeting.
- TOF section in detector chapter by Maurizio, Mauro, Alberto.

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

##  measurement precision can be as good as out/ in ) = 10-3

**T.O.F. III**
**Precise timing**

**Electron ID**
**Eliminate muons that decay  **

**Tracking devices: **
**He filled TPC-GEM (similar to TSLA R&D)**
**or sci-fi**
**Measurement of momentum angles and position**

**T.O.F. I & II**
**Pion /muon ID**
**precise timing**

** ****10% cooling of 200 MeV muons requires ~ 20 MV of RF**
_** **__**single particle measurements**_** =>**
** ****measurement precision can be as good as ********out****/******** in ****) = 10****-3**

**201 MHz RF**** ****cavities**

**Liquid H2 absorbers**
**or LiH ?**

**SC Solenoids;**
**Spectrometer, focus pair, compensation coil**

**LOI submitted to PSI and RAL. **
**The two labs agreed to collaborate and RAL encourages submission of proposal. 2002: prepare proposal.**** **

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## TOF I Station

- TOF I is located after 1st diffuser where beam comes into hall.
- This at  –15 meters from center of cooling cells.
- TOF I is 1212 cm2 in size.
- TOF I is composed of two planes oriented in X and Y respectively
- Each plane is segmented into two slabs with phototubes on each end.
- Each slab is 1262.5 cm3.
- Using Bicron BC-420 fast Scintillator.
- Use Hamamatsu R4998 Phototubes on each end.
- 0.7 ns rise time, 160 ps transit time jitter

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## TOF II AND TOF III Stations

- TOF II (TOF III) is located before (after) the upstream (downstream) measurement solenoid.
- This is at –5.544 meters from the center of the cooling cells.
- TOF II, III are 4040 cm2 in size.
- TOF II, III are composed of a single Y oriented plane.
- The plane is segmented into 8 slabs.
- Each slab is 4062.5 cm3.
- There is ~1 cm overlap at the edges of the slabs to allow cross-calibration.
- Bicron BC-404 Scintillator is used for these stations since it has a longer attenuation length than the BC-420 used in station I.
- =1.7 meters.

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## TOF II and III continued

- The choice of phototube to use for the TOF II and TOF III stations is complicated by the presence of fringing magnetic field from the measurement solenoids.
- The field situation is shown in the following transparencies.
- The fast phototube used for TOF I (R4998) does not tolerate much magnetic field.  The choices are
- Shield the fast Hamamatsu R4998 phototubes.
- Use the Hamamatsu R5505 fine mesh phototube which can handle fields up to ~1 Tesla.

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## Magnetic Fields in the Vicinity of TOF II

- Figure shows |B| from the cooling and measurement solenoids.
- The parameters used in the calculation come from Rochford et al. (Mice note 10)
- Rcoil = 25 cm !!
- The original sketches show Rcoil=15 cm.
- The phototubes are placed in a place with high field.
- This will be a design issue.

- TOF II ?

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## More on TOF II and TOF III Fields

- Figures show Bz(r) and Br(r) at the TOF II position.
- The phototubes appear to be position at r23-25 cm. (?)
- Bz5 T
- Br0.4 T (this component along is along the phototube axis.
- Light guides could be used to put phototubes outside the coils (hopefully).
- Just outside the coils:
- Bz=2 T
- Br0.3 T
- These are my estimates, not Milano-Padova.

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## Even More on TOF Fields

- The figures on the right show Bz (upper) and Br (lower) at r=25 cm as a function of z.  This is appoximately the radial position that the phototubes would be placed.
- Could we imagine positioning the TOFs ~2.5 meters from the end of the measurement solenoids where the fields will have dropped off?
- This would add ~5 meters to the length.   Can we still do that?

- Bz

- Br

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## Phototube Properties

- The table shows a summary of the phototube properties
- The Hamamatsu R4998 is the faster tube and could be used for TOF I.
- The approach for TOF II, III could be either:
- Multiple mu-metal shielding for a reduction by 106.
- The use of the slower Hamamatsu R 5505 tube
- How much would this compromise the triggering performance?

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## Shielding Phototubes

- Fields transverse to cylinder axis can be effectively reduced
- Single cylinder:
- Three concentric cylinders:
- Numerical estimates using
- Mu-metal =20000
- Thickness =1 mm
- Radii R1=1.5, R2=1.75, R3=2 cm
- Shielding factor of ST107
- Caution mu-metal may not survive very high fields.
- This does not effectively work for longitudinal fields.
- BL falls off as e-l/D which gives SL~2-3.

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## Trigger

- TOF I

- TOF II

- TOF III

- TPG or
- Fiber Tracker

- TOF I

- TOF II

- TOF III

- FTrac I

- FTrac II

- FTrac III

- FTrac IV

- TDC

- DISC

- RF gate

- Modified D0 fiber DAQ

- TDC

- TDC

- TDC

- Gate Gen.

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## TOF Signal Processing

- From the HARP experience the signal processing issues are likely to be
- Electronic Cross Talk in the discriminators and TDCs.
- Time Stability of temperature, etc.
- HARP experiences implies that 150 ps intrinsic resolution can be achieved.  This will require
-  High quality signal cables
- High quality active splitters for PMT signal to TDC, ADC
- Leading edge discriminators modified for cross talk
- High quality delay cables
- High quality signal regenerators to TDC inputs
- State of the art TDCs
- Much of this will be available from HARP

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## Time of Flight System Costs

- MICE TOF -- Kahn and Lee

- Oct 24, 2002

## What Needs to be Studied

- Understand what the field environment will be at the position of the PMTs.
- Photomultiplier Tube performance in our magnetic field environment.
- PMT coupling to directly to scintillator for TOF I
- Light guide shape and length for TOF II, III to live with field.
- Can we used the faster PMTs with shielding.
- Triggering for the MICE experiment.

- MICE TOF -- Kahn and Lee

- Oct 24, 2002