To do for the next K0 beam time

To do for the next K0 To do for the next K0 beam timebeam time

Department of Physics,Department of Physics,Tohoku UniversityTohoku University

H. KandaH. Kanda

18 Aug. 2006 LNS Nuclear Physics Working Group

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““Next” what?Next” what?

The next beam times in SeptemberThe next beam times in September Preparation status of the LD2 target and a Preparation status of the LD2 target and a

vacuum gamma beam duct vacuum gamma beam duct The coming beam time already proposed The coming beam time already proposed

and approvedand approved Neutron detector for NKS2Neutron detector for NKS2 Beam profile monitorBeam profile monitor

The experimental plan to be proposed in the The experimental plan to be proposed in the near futurenear future Investigation of “quasi-freedom” of deuteron Investigation of “quasi-freedom” of deuteron

targettarget


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Preparation of the LD2 targetPreparation of the LD2 target

We have modified our LD2 targetWe have modified our LD2 target elongation of the insertion part to fit the elongation of the insertion part to fit the

dimension of the 680 magnetdimension of the 680 magnet new TMP port for speeding up the vacuum new TMP port for speeding up the vacuum

pumpingpumping Direct attachment of the TMP greatly Direct attachment of the TMP greatly

worked to shorten the pumping periodworked to shorten the pumping periodOld cryostat: Roughly 1 night to pump Old cryostat: Roughly 1 night to pump down to 1x10down to 1x10-5-5 mbar for starting the mbar for starting the refrigeratorrefrigeratorNew cryostat: Only 1 hour to pump! New cryostat: Only 1 hour to pump!


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Preparation of the LD2 targetPreparation of the LD2 target Elongation should have changed the thermElongation should have changed the therm

al condition inside the cryostat which will fal condition inside the cryostat which will force modification of the liquefaction and vorce modification of the liquefaction and vapor-suppressing method. apor-suppressing method.

Vapor-suppression is essential to reduce tVapor-suppression is essential to reduce the ambiguity of the target density. Howevehe ambiguity of the target density. However, vapor suppressed state is identified only r, vapor suppressed state is identified only by a phase diagram.by a phase diagram.

We have to re-build the vapor-suppression We have to re-build the vapor-suppression method for the new cryostat and see the limethod for the new cryostat and see the liquid without any vapor bubbles by our eyequid without any vapor bubbles by our eyes. And the test of the long term (~ one wes. And the test of the long term (~ one week) stability is prefered.ek) stability is prefered.

These test should be finished until These test should be finished until mid-Semid-Septemberptember for the installation and the stable for the installation and the stable operation in the next next beam time.operation in the next next beam time.

Time course of the temperatures and phase diagram measured by the old cryostat.

Operation point


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What’s the trouble?What’s the trouble? The liquid deuterium is consisted of ICF34 flange, an The liquid deuterium is consisted of ICF34 flange, an

aluminum shell (EB-welded), the polyimide film (adhered on aluminum shell (EB-welded), the polyimide film (adhered on the aluminum shell), and a flange for the liquid temperature the aluminum shell), and a flange for the liquid temperature monitor (sealed by an indium wire).monitor (sealed by an indium wire).

Gas leak happened when the cell is refrigerated down to Gas leak happened when the cell is refrigerated down to 150 ~ 200 K.150 ~ 200 K.

REFINED: adhering method of polyimide film, tightening of REFINED: adhering method of polyimide film, tightening of ICF flange, tightening of indium sealICF flange, tightening of indium seal

LEAK TESTED (in LN2): an ICF flange, film surfaces, and LEAK TESTED (in LN2): an ICF flange, film surfaces, and adhered surfacesadhered surfaces

TESTED but NOT ISOLATED: indium seal and flange for the TESTED but NOT ISOLATED: indium seal and flange for the thermometer (thermometer is adhered through the hole of thermometer (thermometer is adhered through the hole of the flange)the flange)

The flange for the thermometer is now the most suspicious The flange for the thermometer is now the most suspicious for the source of the leakage. The isolation of the seal and for the source of the leakage. The isolation of the seal and the flange itself is quit difficult... Blank flange is needed to the flange itself is quit difficult... Blank flange is needed to be relieved that the seal is good. be relieved that the seal is good.


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Preparation of the vacuum gamma Preparation of the vacuum gamma beam ductbeam duct

Gamma beam travels through the air as lGamma beam travels through the air as long as 3.2 m (1.1x10ong as 3.2 m (1.1x10-2-2 X X00) after the colli) after the collimator to the target.mator to the target.

A vacuum duct of 2 m long (4.4x10A vacuum duct of 2 m long (4.4x10-3-3 X X0 0 inincluding film-windows: 50cluding film-windows: 50m, and the remm, and the remaining air) reduced the trigger rate by 30aining air) reduced the trigger rate by 30 % with % with Tag=2MHz and 2mm thick acryliTag=2MHz and 2mm thick acrylic target. c target.

A vacuum duct of 3 m long (9.9x10A vacuum duct of 3 m long (9.9x10-4-4 X X00) i) is now planned to replace the old one. Ths now planned to replace the old one. Thinner film (25inner film (25m) will be used. The new m) will be used. The new one is estimated to reduce the trigger ratone is estimated to reduce the trigger rate by 45 %.e by 45 %.

Plan view of the pair magnet,the 680 magnet, and some elementsfor gamma beam line.

gammabeam

Pair magnet

pump

~3.0m

Piranigauge


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Neutron detectorNeutron detector Multi-pion photoproduction experimMulti-pion photoproduction experim

ent: LNS Exp#2551 was approved lent: LNS Exp#2551 was approved last year to run with the K0 photoproast year to run with the K0 photoproduction experiment: #2552. In the duction experiment: #2552. In the proposal, I commented to place the proposal, I commented to place the neutron detector at the forward of tneutron detector at the forward of the NKS2.... No preparation is carriehe NKS2.... No preparation is carried out so far.d out so far.

However, the neighbor of the NKS2 However, the neighbor of the NKS2 is too crowded now to place the largis too crowded now to place the large object as the neutron detector (a e object as the neutron detector (a passage will be lost).passage will be lost).


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Beam profile monitorBeam profile monitor The only solution to make room The only solution to make room

for the neutron detector is to refor the neutron detector is to remove the HSBPM by Ishikawa-smove the HSBPM by Ishikawa-san and Koutaku-san, which playan and Koutaku-san, which played the important role in the beaed the important role in the beam tuning period.m tuning period.

X-ray imaging camera “Remote X-ray imaging camera “Remote RadEye” might be one of the goRadEye” might be one of the good replacements of the HSBPM od replacements of the HSBPM and Polaroid films. Thanks to its and Polaroid films. Thanks to its small size, it will be easy to plasmall size, it will be easy to place it on the Lead glass counter.ce it on the Lead glass counter.


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Investigation of “quasi-freedom” of Investigation of “quasi-freedom” of the deuteron targetthe deuteron target

In our result of pion photoproduction on proton and deuteron, interesIn our result of pion photoproduction on proton and deuteron, interesting phenomena could be seen.ting phenomena could be seen. The double pion photoproduction cross sections on free proton are consiThe double pion photoproduction cross sections on free proton are consi

stent with the results from other experiments.stent with the results from other experiments. The cross sections on quasi-free proton, namely proton in deuteron, are The cross sections on quasi-free proton, namely proton in deuteron, are

smaller than the results from other experiments. They resemble to the dsmaller than the results from other experiments. They resemble to the double pion photoproduction cross sections on quasi-free neutron.ouble pion photoproduction cross sections on quasi-free neutron.

The single pion photoproduction cross sections are in good agreement wThe single pion photoproduction cross sections are in good agreement with the other results. ith the other results.

Can deuteron be considered as the quasi-free target of nucleon? WhiCan deuteron be considered as the quasi-free target of nucleon? Which is the most likely view, in these words as quasi-, semi-, pseudo-, ch is the most likely view, in these words as quasi-, semi-, pseudo-, non-, and anti-?non-, and anti-?

Detailed analysis for final states will reveal more precise view of the Detailed analysis for final states will reveal more precise view of the “quasi-freedom” of the deuteron. (needs hermetic detector system a“quasi-freedom” of the deuteron. (needs hermetic detector system and more statistics)nd more statistics)


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Cross sections for Cross sections for p -> pp -> p++- - and gand gp -> p -> ++++--


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Cross sections for g”p” -> pCross sections for g”p” -> p++- - comcompared with other results for “p” targpared with other results for “p” targ

et and “n” target et and “n” target


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Cross sections for Cross sections for d -> ppd -> pp--


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SummarySummary

I’m sorry for the delay of the preparation of I’m sorry for the delay of the preparation of the liquid deuterium target.the liquid deuterium target.

I’m sorry for the delay of the preparation of I’m sorry for the delay of the preparation of a neutron detector.a neutron detector.

Pion photoproduction experiment showed aPion photoproduction experiment showed an interesting results. Detailed investigation n interesting results. Detailed investigation will provide us of more interesting results.will provide us of more interesting results.

To do for the next K0 beam time

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