[Tpe] TPE shielding

[Larry Weinstein]

Dear Dave,

Thank you very much.  We will probably want to build this wall during 
the next major down time, possibly Tuesday.

- Larry

David Kashy wrote:
> Hello Larry,
> I have verified that we can stack a concrete wall up to 5 ft high and 
> 10 ft long on the decking next to the pair spectrometer magnet if 
> necessary. I used a block density of 150 lb/cubic ft. I think this is 
> what we have.
>
>
> Thanks
> Dave
>
>
>
>>>>>
>>>>>
>>>>> On 1/26/2011 4:55 PM, Larry Weinstein wrote:
>>>>>> Dear Folks,
>>>>>>
>>>>>> Recommendation: In order to be very conservative, build a 
>>>>>> concrete wall on the beam left side of the collimator box, 
>>>>>> frascati magnet 1, and PS magnet.  The wall would be about 10' x 
>>>>>> 5' x 1' and require 200 blocks.  It should be built during the 
>>>>>> next extended down time (Tuesday?) so as not to interfere with 
>>>>>> taking data.
>>>>>>
>>>>>> Details:  I spoke to Pavel Degtiarenko, the radiation and 
>>>>>> shielding expert.  He says that there is very little useful data 
>>>>>> about the effect of radiation on electronics because the response 
>>>>>> of electronics to radiation is highly variable.  He also noted 
>>>>>> that the existing BPM amplifiers have probably already suffered 
>>>>>> some radiation damage and that this damage is cumulative.  He 
>>>>>> also said that most of the radiation is probably high energy 
>>>>>> particles that can be shielded by a shield wall (if we know the 
>>>>>> approximate source location.)
>>>>>>
>>>>>> This means that we probably want to add shielding to reduce the 
>>>>>> probability of catastrophic BPM failure.
>>>>>>
>>>>>> RadCon gave us the badge readings today (thanks, Becky!).
>>>>>>
>>>>>> 66016 	331 	1' from top of Acc IOC rack 	
>>>>>> 66017 	197 	2.5' from top of Acc IOC rack, in front of concrete wall
>>>>>> 66018 	220 	2.5' from bottom of Acc IOC rack, in front of 
>>>>>> concrete wall
>>>>>> 66019 	66 	2.5 from top of Acc IOC rack, behind concrete wall
>>>>>> 66020 	73 	2' from bottom of Acc IOC rack, behind concrete wall
>>>>>> 66023 	92 	on ioc ptarg 	
>>>>>> 	
>>>>>> 	
>>>>>> 66024 	254 	in front of new lead wall, 5' from floor 	
>>>>>> 66025 	191 	L1-15 on left (upstream) side of IOC 	
>>>>>> 66026 	632 	on railing opposite PS 	
>>>>>> 	
>>>>>> 66027 	230 	upstream, beam side of lead wall on ioctorus
>>>>>> 66028 	126 	downstream, outside of lead wall on ioc torus
>>>>>>
>>>>>> The first column is the badge number, the second is the radiation 
>>>>>> dose, and the third is the location.
>>>>>>
>>>>>> A few notes: Badge 66026 with a reading of 632 mr is located 
>>>>>> where the radcon photon probe was located before 1/20, on the 
>>>>>> railing of the space frame close to the pair spectrometer.  The 
>>>>>> probe was reading about 50 mr/hr at that location.
>>>>>>
>>>>>> Badge 66019, behind the concrete wall, is located directly on top 
>>>>>> of the accelerator BPM amplifiers and right next to the radcon 
>>>>>> photon probe which is currently reading 5 mr/hr.  This is 
>>>>>> consistent with badge 66026.
>>>>>>
>>>>>> badges 66016, 7, and 8 are located on the accelerator BPM 
>>>>>> amplifier rack.  The highest one (66016) has the highest dose and 
>>>>>> has much less of the lead shielding on the lead wall between it 
>>>>>> and the beam line.  The concrete wall (either 6" or 12") reduces 
>>>>>> the rate from about 200 mr to 70 mr (comparing badges 17 and 18 
>>>>>> with 19 and 20).  (Note that the badges were placed before the 
>>>>>> BPE shielding was added.)
>>>>>>
>>>>>> The maximum thickness of the lead wall reduces the dose from 254 
>>>>>> (badge 66024) to 92 (badge 66023).
>>>>>>
>>>>>> The radiation level is not much less a little further down-beam 
>>>>>> on rack L1-15 (191 mr at badge 25).
>>>>>>
>>>>>> The dose decreases about a factor of two between the upstream 
>>>>>> beam side of the lead wall on ioctorus to the downstream outside 
>>>>>> of the lead wall.
>>>>>>
>>>>>> Summary: The dose at iocptarg, ioctorus and the accelerator BPM 
>>>>>> amplifiers are within a factor of two.  The shielding reduces the 
>>>>>> dose significantly.
>>>>>>
>>>>>> There is floor space or floor weight capacity to place any more 
>>>>>> shielding near the racks.  THis means that the only place to add 
>>>>>> shielding is near the source.  Since the source probably includes 
>>>>>> the collimator box, convertor and chicane, we should build a 
>>>>>> concrete wall on the beam left side from the PS magnet going as 
>>>>>> far upstream as possible.
>>>>>>
>>>>>> -- 
>>>>>> 				Sincerely,
>>>>>> 				Larry
>>>>>>
>>>>>> -----------------------------------------------------------
>>>>>> Lawrence Weinstein
>>>>>> University Professor
>>>>>> Physics Department
>>>>>> Old Dominion University
>>>>>> Norfolk, VA 23529
>>>>>> 757 683 5803
>>>>>> 757 683 3038 (fax)
>>>>>> weinstein at odu.edu  <mailto:weinstein at odu.edu>
>>>>>> http://www.lions.odu.edu/~lweinste/  <http://www.lions.odu.edu/%7Elweinste/>

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