Opportunities for the
decay searchat U-70 synchrotron (IHEP, Protvino)
A. Ostankov for the KLOD collaboration
Joint Project :IHEP, Protvino
JINR, Dubna
INR, Moscow, RAS

Proposal– published as IHEP Preprint 2007-08– reported at KAON-07– some materials are available at http://kaon.jinr.ru/

STATE RESEARCH CENTER OF RUSSIA
INSTITUTE FOR HIGH ENERGY PHYSICS
Stable operation last few years

70 GeV IHEP proton synchrotron

2 running periods per year 30÷40 days each
Normally (20÷30)×2 days available for physicist in a year
Extra beam time is technically possible. ($1M per Run)

Constantly under development & improvement
Last years achievements:
Increasing intensity (1013 ppp – nominal condition)• 2×1013 already achieved (stable @60GeV)• 3×1013 unstable @present• 5×1013 possible (H+)
Spill duration
Stochastic Slow Extracted Proton Beam regime implemented in 2006
60 GeV protons, 8 sec period / 3 sec flat top
Note: Spill duration is limited by possible accelerating field plateau (heating)(2 – 3 – 4)sec @ (70 – 60 – 50) GeV correspondingly

For our estimation we considered1013 ppp @60GeV, 3 sec spill

K L0

KLOD Detector-- Measurement strategy similar to KAMI, E391a, K0TO
narrow beam approach, Kaon bottle-- Sensitivity is compatible to J-Parc(2)in consideration of U-70 intensity reserve (2×1013 ppp),
but note beam time available-- Worse Signal/Background ratio
due to beam size

The current work on
theproject
KLOD
includes in particular
the R&D for the most
crucial detectors:-- In-Beam Veto-- Main Barrel Veto-- … …
The data were taken from the original Proposals without recalculations and tracking the values changes

Main Veto Prototypes-- Main Veto dominates in overall cost estimation-- Best γ-detection efficiency up to the smallest energy is needed¾¾To our opinion the fine Shashlyk-structure (0.3mm Pb + 1.5mm molding Scint.) is
the best choice to keep detection threshold low
Stair-like shape – to avoid any possible gaps

Mirrored Fibers

Prototyping goal -- to demonstrate the capability of manufacturing self-supporting
modules of such type + mass scale production technology development

Fiber Loops

By beam test we confirmed:• ≈ 30000 photons per 1 GeV γ-shower• ≈ 5 ph.e– per single Scint. plate for m.i.p.
• ≈ 15 ph.e– per 1 MeV of “visible” energy• σE/E ≈ 3%/sqrt(E)In-Beam Veto-Calorimeter – real challenge
Problems:

1. γ-detection from background decays in apertureof high int. beam
2% ofhave 2 γ’s (π0) at In BeamVetosuch topology should be suppressed, 10-6 !!!
hard spectrum (fortunately)
2. avoid “over-veto” (acceptance lost) from the beam
particles misidentified as a γ’s~300 MHz neutron flux – major problemSolutions:
1. to use Cherenkov light
Quartz fibers are only sensitive to em shower component
CMS HF: e/h ~ 5, NIM A399 (1997) 202
2. Dual Readout (Scint.+Ch.)
It’s proven by DREAM collaboration that Scint. and Ch.
signals have different behaviors for em and had. showers,
NIM A536 (2005) 29

3. +++++

enough amount of X0’s
small amount of λ’svery fastsegmentations
no dead time readout (FADC)

In-Beam Veto-Calorimeter Prototype
Structure along the beam: (0.3mm Pb + 1mm Acril + 1.5 mm Scint.) × 100 layers
Segmentation: -- across the beam (Y, in one direction only): 17mm (17 fibers) × 5 cells-- along the beam, (Z): 20 layers × 5 cells
Elementary cell: 200mm (X) × 17mm (Y) × 60mm (Z)Full prototype: (200 mm × 85 mm × 100 layers)Î ≈ (1RM × 2RM × 7.5X0)
The purpose is to look at Ch/Sc signals ratio & its behavior
in transverse and longitudinal directions

Energy resolution for γ’s:
σE/E ~ 5.5%/√Е by Scint.
σE/E ~ 7.6%/√Е by Cher.
For γ’s (at full energy range studied):R0 = Ch/Scint ≈ 0.075
σR/R0 ≈ 8%/√Е

Scint. Signal (arb.)

In-Beam Veto-Calorimeter Monte-Carlo

R=Ch./Scint.

R=Ch./Scint.

The simplest algorithm for γ-shower recognition, registered R=(R0 ± 3σR(EScint)),
suppress n-component by factor of ~100 Î (300 Æ3) MHz n-flux Î ~2% acceptance lost (10 nsec)

Preliminary beam test (Spring 2009)
Prototype partially equipped by PMT’s (20 channels out of 50) => only μ-Runs are relevant
Uniformity:
Light yield:+/− 5% in both directions across the beam
10 ph.e from Cherenkov light per single cell @45o for m.i.p.
=> 0.5 ph.e per fiber layer.
Scint./Cher. = 10
Response vs. angle of incidence:
for Cher. -- max. at @45o, proper angular behavior
no dependence for Scint. Light
Data will be used for fine Monte-Carlo tuning.
In absence on n-beam only indirect proofs of working capabilities of device are possible

To conclude
The current status of the KLOD project is as follows: there arethree working groups from three scientific centers of RussianFederation (JINR, IHEP, INR) belonging to different Ministries withindependent financings. The Scientific Committees of IHEP, JINR andINR have clearly recognized the scientific importance of thisexperiment.
The financial situation is that, at present, 3 Institutes will not
be able to provide needed money resources in the framework of existing
budgets. It means that somehow we'll have to obtain an independent
dedicated financing or/and to involve more participants.
However, there are enough resources for the R&D phase andthe common will is to do it. In parallel, at IHEP a detailed calculations
related to the beam are in progress, as well as the Technical Proposal
preparation for the beam-line.